From 67f1a5d15d9cb3814251dd6569fd7c977826742f Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Tue, 20 Feb 2024 00:42:23 +0900
Subject: [PATCH 01/40] Cleanup `pair` type constructor

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                           |  6 +++---
 VERSION                             |  2 +-
 include/meevax/kernel/pair.hpp      | 13 +++++++------
 include/meevax/memory/collector.hpp |  8 +++++---
 src/kernel/pair.cpp                 |  8 --------
 5 files changed, 16 insertions(+), 21 deletions(-)

diff --git a/README.md b/README.md
index 6a483660c..d4afe7081 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.119_amd64.deb
+sudo apt install build/meevax_0.5.120_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.119.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.120.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.119_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.120_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index e8b2b30cf..0a7839ea8 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.119
+0.5.120
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index a5b02366f..cecb4ae84 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -138,13 +138,14 @@ inline namespace kernel
 
     constexpr pair() = default;
 
-    explicit pair(object const&);
-
-    explicit pair(object const&, object const&);
+    template <typename T, typename U = decltype((unit)), REQUIRES(std::is_constructible<std::pair<object, object>, T, U>)>
+    explicit pair(T&& x, U&& y = unit)
+      : std::pair<object, object> { std::forward<decltype(x)>(x), std::forward<decltype(y)>(y) }
+    {}
 
-    template <typename... Ts, typename = std::enable_if_t<(1 < sizeof...(Ts))>>
-    explicit pair(object const& a, Ts&&... xs)
-      : pair { a, make<pair>(std::forward<decltype(xs)>(xs)...) }
+    template <typename T, typename... Ts, typename = std::enable_if_t<(1 < sizeof...(Ts))>>
+    explicit pair(T&& x, Ts&&... xs)
+      : std::pair<object, object> { std::forward<decltype(x)>(x), make<pair>(std::forward<decltype(xs)>(xs)...) }
     {}
 
     virtual ~pair() = default;
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 0c9675431..075fe5703 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -18,10 +18,12 @@
 #define INCLUDED_MEEVAX_MEMORY_COLLECTOR_HPP
 
 #include <cstddef>
+#include <memory>
+#include <unordered_map>
 
 #include <meevax/memory/literal.hpp>
 #include <meevax/memory/marker.hpp>
-#include <meevax/memory/pointer_set.hpp>
+#include <meevax/memory/integer_set.hpp>
 
 namespace meevax
 {
@@ -181,9 +183,9 @@ inline namespace memory
   protected:
     static inline tag * cache = nullptr;
 
-    static inline v2::pointer_set<tag *> tags {};
+    static inline integer_set<tag *, 16, 16, 16> tags {};
 
-    static inline v2::pointer_set<mutator *> mutators {};
+    static inline integer_set<mutator *, 16, 16, 16> mutators {};
 
     static inline std::size_t allocation = 0;
 
diff --git a/src/kernel/pair.cpp b/src/kernel/pair.cpp
index 3d8ca0305..2a23c408d 100644
--- a/src/kernel/pair.cpp
+++ b/src/kernel/pair.cpp
@@ -22,14 +22,6 @@ inline namespace kernel
 {
   let unit { nullptr };
 
-  pair::pair(object const& a)
-    : std::pair<object, object> { a, unit }
-  {}
-
-  pair::pair(object const& a, object const& b)
-    : std::pair<object, object> { a, b }
-  {}
-
   auto pair::compare(pair const* that) const -> bool
   {
     return that and *this == *that;

From 3c206cdc133742e723fd58eebb5079ac7e322679 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Tue, 20 Feb 2024 02:37:11 +0900
Subject: [PATCH 02/40] Remove `format.cpp`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                           |  6 +++---
 VERSION                             |  2 +-
 include/meevax/memory/collector.hpp |  1 +
 src/format.cpp                      | 29 -----------------------------
 4 files changed, 5 insertions(+), 33 deletions(-)
 delete mode 100644 src/format.cpp

diff --git a/README.md b/README.md
index d4afe7081..3f7af7d0a 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.120_amd64.deb
+sudo apt install build/meevax_0.5.121_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.120.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.121.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.120_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.121_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 0a7839ea8..39a32b845 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.120
+0.5.121
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 075fe5703..0906c3b85 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -20,6 +20,7 @@
 #include <cstddef>
 #include <memory>
 #include <unordered_map>
+#include <utility>
 
 #include <meevax/memory/literal.hpp>
 #include <meevax/memory/marker.hpp>
diff --git a/src/format.cpp b/src/format.cpp
deleted file mode 100644
index 583dcf8f6..000000000
--- a/src/format.cpp
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
-   Copyright 2018-2023 Tatsuya Yamasaki.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-#include <meevax/kernel/input_file_port.hpp>
-
-auto main(int const, char const* const* const argv) -> int
-{
-  using namespace meevax;
-
-  for (let const& x : input_file_port(argv[1]))
-  {
-    std::cout << x << std::flush;
-  }
-
-  return EXIT_SUCCESS;
-}

From c6163ff1fdfffa9badc6f064764a6625c1a7e7ae Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 25 Feb 2024 00:46:20 +0900
Subject: [PATCH 03/40] Update frequently `make`ed types to allocate memory
 from memory pool

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                       |  6 +++---
 VERSION                                         |  2 +-
 include/meevax/kernel/dynamic_environment.hpp   |  4 ++--
 include/meevax/kernel/pair.hpp                  | 14 +++++---------
 include/meevax/kernel/syntactic_environment.hpp |  2 +-
 include/meevax/memory/collector.hpp             |  4 ++--
 include/meevax/memory/heterogeneous_pointer.hpp |  2 +-
 include/meevax/memory/simple_allocator.hpp      |  2 ++
 src/kernel/boot.cpp                             |  2 +-
 9 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/README.md b/README.md
index 3f7af7d0a..eb66971f5 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.121_amd64.deb
+sudo apt install build/meevax_0.5.122_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.121.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.122.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.121_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.122_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 39a32b845..71b3d8fc7 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.121
+0.5.122
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index 78c15301c..2ca3664f2 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -214,7 +214,7 @@ inline namespace kernel
           *  where <closure> = (c' . e)
           *
           * ----------------------------------------------------------------- */
-          s = cons(make<closure>(cadr(c), e), s);
+          s = cons(make<closure, simple_allocator<void>>(cadr(c), e), s);
           c = cddr(c);
           goto fetch;
 
@@ -225,7 +225,7 @@ inline namespace kernel
           *  where <continuation> = (s e c' . d)
           *
           * ----------------------------------------------------------------- */
-          s = cons(list(make<continuation>(s, e, cadr(c), d)), s);
+          s = cons(list(make<continuation, simple_allocator<void>>(s, cons(e, cons(cadr(c), d)))), s);
           c = cddr(c);
           goto fetch;
 
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index cecb4ae84..043c39533 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -20,6 +20,7 @@
 #include <meevax/kernel/character.hpp>
 #include <meevax/kernel/instruction.hpp>
 #include <meevax/memory/gc_pointer.hpp>
+#include <meevax/memory/simple_allocator.hpp>
 
 namespace meevax
 {
@@ -43,14 +44,14 @@ inline namespace kernel
             typename... Ts>
   auto make(Ts&&... xs) -> object
   {
-    return object::allocate<T, Allocator>(std::forward<decltype(xs)>(xs)...);
+    return object::make<T, Allocator>(std::forward<decltype(xs)>(xs)...);
   }
 
   template <typename T,
             typename Allocator = collector::default_allocator<void>>
   auto make(T&& x) -> object
   {
-    return object::allocate<std::decay_t<T>, Allocator>(std::forward<decltype(x)>(x));
+    return object::make<std::decay_t<T>, Allocator>(std::forward<decltype(x)>(x));
   }
 
   template <template <typename...> typename Traits,
@@ -143,11 +144,6 @@ inline namespace kernel
       : std::pair<object, object> { std::forward<decltype(x)>(x), std::forward<decltype(y)>(y) }
     {}
 
-    template <typename T, typename... Ts, typename = std::enable_if_t<(1 < sizeof...(Ts))>>
-    explicit pair(T&& x, Ts&&... xs)
-      : std::pair<object, object> { std::forward<decltype(x)>(x), make<pair>(std::forward<decltype(xs)>(xs)...) }
-    {}
-
     virtual ~pair() = default;
 
     virtual auto compare(pair const*) const -> bool;
@@ -192,8 +188,8 @@ inline namespace kernel
   template <typename T, typename U, REQUIRES(std::is_constructible<pair, T, U>)>
   auto operator |(T&& x, U&& y) -> decltype(auto)
   {
-    return make<pair>(std::forward<decltype(x)>(x),
-                      std::forward<decltype(y)>(y));
+    return make<pair, simple_allocator<void>>(std::forward<decltype(x)>(x),
+                                              std::forward<decltype(y)>(y));
   }
 
   inline auto cons = [](auto&&... xs) constexpr
diff --git a/include/meevax/kernel/syntactic_environment.hpp b/include/meevax/kernel/syntactic_environment.hpp
index b428236ee..28df04225 100644
--- a/include/meevax/kernel/syntactic_environment.hpp
+++ b/include/meevax/kernel/syntactic_environment.hpp
@@ -1218,7 +1218,7 @@ inline namespace kernel
              bind("quote-syntax"                   , syntax::quote_syntax                  ),
              bind("set!"                           , syntax::set                           )));
 
-      return make<syntactic_closure>(core_syntactic_environment, unit, make_symbol(variable));
+      return make<syntactic_closure>(core_syntactic_environment, cons(unit, make_symbol(variable)));
     }
 
     inline auto sweep(object const& form,
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 0906c3b85..b90137262 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -22,9 +22,9 @@
 #include <unordered_map>
 #include <utility>
 
+#include <meevax/memory/integer_set.hpp>
 #include <meevax/memory/literal.hpp>
 #include <meevax/memory/marker.hpp>
-#include <meevax/memory/integer_set.hpp>
 
 namespace meevax
 {
@@ -208,7 +208,7 @@ inline namespace memory
     auto operator =(collector const&) -> collector & = delete;
 
     template <typename T, typename Allocator = default_allocator<void>, typename... Ts>
-    static auto make(Ts&&... xs)
+    auto make(Ts&&... xs)
     {
       if (allocation += sizeof(T); threshold < allocation)
       {
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
index 6a7443487..dda140cf9 100644
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ b/include/meevax/memory/heterogeneous_pointer.hpp
@@ -97,7 +97,7 @@ inline namespace memory
     template <typename Bound,
               typename Allocator = collector::default_allocator<void>,
               typename... Us>
-    static auto allocate(Us&&... xs)
+    static auto make(Us&&... xs)
     {
       if constexpr (std::is_same_v<Bound, Top>)
       {
diff --git a/include/meevax/memory/simple_allocator.hpp b/include/meevax/memory/simple_allocator.hpp
index 1c08cbc38..9acba8314 100644
--- a/include/meevax/memory/simple_allocator.hpp
+++ b/include/meevax/memory/simple_allocator.hpp
@@ -107,6 +107,8 @@ class simple_allocator
     }
     else
     {
+      assert(fresh_chunks);
+
       if (not (*fresh_chunks).remaining())
       {
         fresh_chunks = new chunks(fresh_chunks);
diff --git a/src/kernel/boot.cpp b/src/kernel/boot.cpp
index 33151b2b0..86ed3b919 100644
--- a/src/kernel/boot.cpp
+++ b/src/kernel/boot.cpp
@@ -1749,7 +1749,7 @@ inline namespace kernel
 
       library.define<procedure>("make-syntactic-closure", [](let const& xs)
       {
-        return make<syntactic_closure>(car(xs), cadr(xs), caddr(xs));
+        return make<syntactic_closure>(car(xs), cons(cadr(xs), caddr(xs)));
       });
     });
 

From 96f0ccfe44e1becf441da914a1f12932496448c5 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 25 Feb 2024 02:02:42 +0900
Subject: [PATCH 04/40] Update `collector` object to declare it as a global
 variable

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 +-
 VERSION                                       |  2 +-
 include/meevax/memory/collector.hpp           |  6 +-
 .../meevax/memory/heterogeneous_pointer.hpp   |  4 +-
 src/kernel/boot.cpp                           |  4 +-
 src/memory/collector.cpp                      | 20 +++--
 test/collector.cpp                            | 86 +++++++++----------
 test/environment.cpp                          |  7 +-
 test/pair.cpp                                 |  4 +-
 test/vector.cpp                               | 74 ++++++++--------
 10 files changed, 109 insertions(+), 104 deletions(-)

diff --git a/README.md b/README.md
index eb66971f5..decf1101e 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.122_amd64.deb
+sudo apt install build/meevax_0.5.123_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.122.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.123.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.122_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.123_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 71b3d8fc7..260859cac 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.122
+0.5.123
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index b90137262..a54e648dc 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -195,7 +195,7 @@ inline namespace memory
     static inline std::unordered_map<std::string, std::unique_ptr<void, void (*)(void * const)>> dynamic_linked_libraries {};
 
   public:
-    collector() = default;
+    collector();
 
     collector(collector &&) = delete;
 
@@ -208,7 +208,7 @@ inline namespace memory
     auto operator =(collector const&) -> collector & = delete;
 
     template <typename T, typename Allocator = default_allocator<void>, typename... Ts>
-    auto make(Ts&&... xs)
+    static auto make(Ts&&... xs)
     {
       if (allocation += sizeof(T); threshold < allocation)
       {
@@ -246,7 +246,7 @@ inline namespace memory
     static auto sweep() -> void;
   };
 
-  auto primary_collector() -> collector &;
+  extern collector default_collector;
 } // namespace memory
 } // namespace meevax
 
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
index dda140cf9..96f7f4b79 100644
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ b/include/meevax/memory/heterogeneous_pointer.hpp
@@ -101,11 +101,11 @@ inline namespace memory
     {
       if constexpr (std::is_same_v<Bound, Top>)
       {
-        return heterogeneous_pointer(primary_collector().make<Top, Allocator>(std::forward<decltype(xs)>(xs)...));
+        return heterogeneous_pointer(collector::make<Top, Allocator>(std::forward<decltype(xs)>(xs)...));
       }
       else if constexpr (std::is_class_v<Bound>)
       {
-        return heterogeneous_pointer(primary_collector().make<binder<Bound>, Allocator>(std::forward<decltype(xs)>(xs)...));
+        return heterogeneous_pointer(collector::make<binder<Bound>, Allocator>(std::forward<decltype(xs)>(xs)...));
       }
       else
       {
diff --git a/src/kernel/boot.cpp b/src/kernel/boot.cpp
index 86ed3b919..54d8c796b 100644
--- a/src/kernel/boot.cpp
+++ b/src/kernel/boot.cpp
@@ -1309,8 +1309,8 @@ inline namespace kernel
       {
         return make<procedure>(cadr(xs).as<symbol>(),
                                reinterpret_cast<primitive_procedure::signature>(
-                                 primary_collector().dlsym(cadr(xs).as<symbol>(),
-                                                           primary_collector().dlopen(car(xs).as<string>()))));
+                                 collector::dlsym(cadr(xs).as<symbol>(),
+                                                  collector::dlopen(car(xs).as<string>()))));
       });
     });
 
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index 9c5413ba0..cd8f91267 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -29,9 +29,21 @@ namespace meevax
 {
 inline namespace memory
 {
+  collector default_collector {};
+
+  static auto reference_count = 0;
+
+  collector::collector()
+  {
+    ++reference_count;
+  }
+
   collector::~collector()
   {
-    clear();
+    if (not --reference_count)
+    {
+      clear();
+    }
   }
 
   auto collector::clear() -> void
@@ -161,11 +173,5 @@ inline namespace memory
       }
     }
   }
-
-  auto primary_collector() -> collector &
-  {
-    static auto c = collector();
-    return c;
-  }
 } // namespace memory
 } // namespace meevax
diff --git a/test/collector.cpp b/test/collector.cpp
index e5143348e..4a763d90e 100644
--- a/test/collector.cpp
+++ b/test/collector.cpp
@@ -7,7 +7,7 @@ auto main() -> int
 {
   using namespace meevax;
 
-  const auto gc_count = primary_collector().count();
+  const auto gc_count = default_collector.count();
 
   // scope
   {
@@ -16,19 +16,19 @@ auto main() -> int
       let y = make<symbol>("y");
       let z = make<symbol>("z");
 
-      assert(primary_collector().count() == gc_count + 3);
-      primary_collector().collect();
-      assert(primary_collector().count() == gc_count + 3);
+      assert(default_collector.count() == gc_count + 3);
+      default_collector.collect();
+      assert(default_collector.count() == gc_count + 3);
     }
 
-    assert(primary_collector().count() == gc_count + 3);
-    primary_collector().collect();
-    assert(primary_collector().count() == gc_count);
+    assert(default_collector.count() == gc_count + 3);
+    default_collector.collect();
+    assert(default_collector.count() == gc_count);
   }
 
-  assert(primary_collector().count() == gc_count);
-  primary_collector().collect();
-  assert(primary_collector().count() == gc_count);
+  assert(default_collector.count() == gc_count);
+  default_collector.collect();
+  assert(default_collector.count() == gc_count);
 
   // copy
   {
@@ -42,9 +42,9 @@ auto main() -> int
     assert(eqv(x, y));
   }
 
-  assert(primary_collector().count() == gc_count + 1);
-  primary_collector().collect();
-  assert(primary_collector().count() == gc_count);
+  assert(default_collector.count() == gc_count + 1);
+  default_collector.collect();
+  assert(default_collector.count() == gc_count);
 
   // move
   {
@@ -63,17 +63,17 @@ auto main() -> int
     assert(x.is<symbol>());
     assert(x.as<symbol>() == "x");
 
-    assert(primary_collector().count() == gc_count + 1);
-    primary_collector().collect();
-    assert(primary_collector().count() == gc_count + 1);
+    assert(default_collector.count() == gc_count + 1);
+    default_collector.collect();
+    assert(default_collector.count() == gc_count + 1);
 
     assert(x.is<symbol>());
     assert(x.as<symbol>() == "x");
   }
 
-  assert(primary_collector().count() == gc_count + 1);
-  primary_collector().collect();
-  assert(primary_collector().count() == gc_count);
+  assert(default_collector.count() == gc_count + 1);
+  default_collector.collect();
+  assert(default_collector.count() == gc_count);
 
   // proper list
   {
@@ -91,9 +91,9 @@ auto main() -> int
       assert(y.as<symbol>() == "y");
       assert(z.as<symbol>() == "z");
 
-      assert(primary_collector().count() == gc_count + 3);
-      primary_collector().collect();
-      assert(primary_collector().count() == gc_count + 3);
+      assert(default_collector.count() == gc_count + 3);
+      default_collector.collect();
+      assert(default_collector.count() == gc_count + 3);
 
       return list(x, y, z);
     };
@@ -106,9 +106,9 @@ auto main() -> int
     assert(cadr(a).is<symbol>());
     assert(caddr(a).is<symbol>());
 
-    assert(primary_collector().count() == gc_count + 6);
-    primary_collector().collect();
-    assert(primary_collector().count() == gc_count + 6);
+    assert(default_collector.count() == gc_count + 6);
+    default_collector.collect();
+    assert(default_collector.count() == gc_count + 6);
 
     assert(length(a) == 3);
 
@@ -117,9 +117,9 @@ auto main() -> int
     assert(caddr(a).is<symbol>());
   }
 
-  assert(primary_collector().count() == gc_count + 6);
-  primary_collector().collect();
-  assert(primary_collector().count() == gc_count);
+  assert(default_collector.count() == gc_count + 6);
+  default_collector.collect();
+  assert(default_collector.count() == gc_count);
 
   // improper list
   {
@@ -137,7 +137,7 @@ auto main() -> int
       assert(b.as<symbol>() == "b");
       assert(c.as<symbol>() == "c");
 
-      assert(primary_collector().count() == gc_count + 3);
+      assert(default_collector.count() == gc_count + 3);
 
       return circular_list(a, b, c);
     };
@@ -149,7 +149,7 @@ auto main() -> int
     assert(caddr(x).as<symbol>() == "c");
     assert(cadddr(x).as<symbol>() == "a");
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(car(x).as<symbol>() == "a");
     assert(cadr(x).as<symbol>() == "b");
@@ -157,28 +157,28 @@ auto main() -> int
     assert(cadddr(x).as<symbol>() == "a");
   }
 
-  primary_collector().collect();
+  default_collector.collect();
 
   // change class
   {
     let x = make<symbol>("hoge");
 
-    primary_collector().collect();
+    default_collector.collect();
 
-    assert(primary_collector().count() == gc_count + 1);
+    assert(default_collector.count() == gc_count + 1);
     assert(x.is<symbol>());
     assert(x.as<symbol>() == "hoge");
 
     x = make<exact_integer>(42);
 
-    primary_collector().collect();
+    default_collector.collect();
 
-    assert(primary_collector().count() == gc_count + 1);
+    assert(default_collector.count() == gc_count + 1);
     assert(x.is<exact_integer>());
     assert(x.as<exact_integer>() == 42);
   }
 
-  primary_collector().collect();
+  default_collector.collect();
 
   // number
   {
@@ -194,22 +194,22 @@ auto main() -> int
       assert(y.as<double>() == 42);
     }
 
-    assert(primary_collector().count() == gc_count);
-    primary_collector().collect();
-    assert(primary_collector().count() == gc_count);
+    assert(default_collector.count() == gc_count);
+    default_collector.collect();
+    assert(default_collector.count() == gc_count);
   }
 
-  primary_collector().collect();
+  default_collector.collect();
 
   // read list
   {
-    const auto gc_count = primary_collector().count();
+    const auto gc_count = default_collector.count();
 
     input_string_port("(a a a)").read();
 
-    primary_collector().collect();
+    default_collector.collect();
 
-    assert(primary_collector().count() == gc_count + 1);
+    assert(default_collector.count() == gc_count + 1);
   }
 
   return EXIT_SUCCESS;
diff --git a/test/environment.cpp b/test/environment.cpp
index a0b2b51ff..3e0a0957b 100644
--- a/test/environment.cpp
+++ b/test/environment.cpp
@@ -21,7 +21,7 @@ auto main() -> int
     assert(interaction_environment().is<environment>());
   }
 
-  const auto gc_count = primary_collector().count();
+  const auto gc_count = default_collector.count();
 
   assert(gc_count == specials_count);
 
@@ -38,10 +38,9 @@ auto main() -> int
 
   assert(libraries().empty());
 
-  primary_collector().collect();
-  primary_collector().collect(); // for vector type
+  default_collector.collect();
 
-  assert(gc_count - 1 == primary_collector().count()); // -1 is interaction_environment
+  assert(gc_count - 1 == default_collector.count()); // -1 is interaction_environment
 
   return EXIT_SUCCESS;
 }
diff --git a/test/pair.cpp b/test/pair.cpp
index 5d7508263..b0e969d17 100644
--- a/test/pair.cpp
+++ b/test/pair.cpp
@@ -15,12 +15,12 @@ auto main() -> int
   assert((make<pair, meevax::simple_allocator<void>>().is<pair>()));
 
   /*
-     Without this explicit call to primary_collector().clear(), illegal memory
+     Without this explicit call to default_collector.clear(), illegal memory
      access by the destructor of the collector will occur for objects allocated
      by allocators other than std::allocator. See the comments attached to
      collector::tagged::allocator for a detailed description of this problem.
   */
-  primary_collector().clear();
+  default_collector.clear();
 
   return EXIT_SUCCESS;
 }
diff --git a/test/vector.cpp b/test/vector.cpp
index ebf9772c0..ef5cac3f4 100644
--- a/test/vector.cpp
+++ b/test/vector.cpp
@@ -8,45 +8,45 @@ auto main() -> int
 {
   using namespace meevax;
 
-  const auto gc_count = primary_collector().count();
+  const auto gc_count = default_collector.count();
 
   // make-vector
   {
     let const v = make<vector>(list(make<symbol>("a"),
                                     make<symbol>("b"),
                                     make<symbol>("c")));
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(primary_collector().count() == gc_count + 1);
+    assert(default_collector.count() == gc_count + 1);
   }
 
-  primary_collector().collect();
+  default_collector.collect();
 
   // list->vector
   {
@@ -56,38 +56,38 @@ auto main() -> int
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 7);
+    assert(default_collector.count() == gc_count + 7);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(primary_collector().count() == gc_count + 1);
+    assert(default_collector.count() == gc_count + 1);
   }
 
-  primary_collector().collect();
+  default_collector.collect();
 
   // list->vector
   {
-    auto const gc_count = primary_collector().count();
+    auto const gc_count = default_collector.count();
 
     let const v = make<vector>(input_string_port("(a b c)").read());
 
@@ -97,31 +97,31 @@ auto main() -> int
     assert(v.as<vector>().vector[1].as<symbol>() == "b");
     assert(v.as<vector>().vector[2].as<symbol>() == "c");
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
     assert(v.as<vector>().vector[0].as<symbol>() == "a");
     assert(v.as<vector>().vector[1].as<symbol>() == "b");
     assert(v.as<vector>().vector[2].as<symbol>() == "c");
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
     assert(v.as<vector>().vector[0].as<symbol>() == "a");
     assert(v.as<vector>().vector[1].as<symbol>() == "b");
     assert(v.as<vector>().vector[2].as<symbol>() == "c");
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
@@ -129,45 +129,45 @@ auto main() -> int
 
   symbols().clear();
 
-  primary_collector().collect();
+  default_collector.collect();
 
   // vector literal
   {
-    auto const gc_count = primary_collector().count();
+    auto const gc_count = default_collector.count();
 
     let const v = input_string_port("#(a b c)").read();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
 
-    primary_collector().collect();
+    default_collector.collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(primary_collector().count() == gc_count + 4);
+    assert(default_collector.count() == gc_count + 4);
   }
 
   symbols().clear();
 
-  primary_collector().collect();
+  default_collector.collect();
 
   // vector constructor
   {

From 880102a3c3dd772620ca111dcbf80e4c09f971a2 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 25 Feb 2024 02:16:48 +0900
Subject: [PATCH 05/40] Remove `std::uint32_t` from types where the `object`
 type can be boxed

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                          |  6 +++---
 VERSION                            |  2 +-
 include/meevax/kernel/identity.hpp |  2 +-
 include/meevax/kernel/pair.hpp     |  7 +------
 src/kernel/comparator.cpp          |  2 +-
 test/nan_boxing_pointer.cpp        | 24 ++++++++++++------------
 6 files changed, 19 insertions(+), 24 deletions(-)

diff --git a/README.md b/README.md
index decf1101e..3768fde35 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.123_amd64.deb
+sudo apt install build/meevax_0.5.124_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.123.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.124.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.123_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.124_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 260859cac..d21b1e44b 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.123
+0.5.124
diff --git a/include/meevax/kernel/identity.hpp b/include/meevax/kernel/identity.hpp
index 4b128e6ff..68ff48d0a 100644
--- a/include/meevax/kernel/identity.hpp
+++ b/include/meevax/kernel/identity.hpp
@@ -25,7 +25,7 @@ inline namespace kernel
 {
   struct identity
   {
-    using index = std::uint32_t;
+    using index = std::int32_t;
   };
 
   struct absolute : public virtual pair // (<identifier> . <object>)
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 043c39533..4b7e902d6 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -28,12 +28,7 @@ inline namespace kernel
 {
   struct pair;
 
-  using object = gc_pointer<pair,
-                            bool,
-                            std::int32_t, std::uint32_t,
-                            float,
-                            character,
-                            instruction>;
+  using object = gc_pointer<pair, bool, std::int32_t, float, character, instruction>;
 
   using let = object;
 
diff --git a/src/kernel/comparator.cpp b/src/kernel/comparator.cpp
index e58ec3c0b..59825f240 100644
--- a/src/kernel/comparator.cpp
+++ b/src/kernel/comparator.cpp
@@ -35,7 +35,7 @@ inline namespace kernel
 
   auto union_find(object const& x, object const& y, std::unordered_map<object, object> & forest)
   {
-    using rank = std::uint32_t;
+    using rank = std::int32_t;
 
     if (auto iterator_x = forest.find(x); iterator_x != forest.end())
     {
diff --git a/test/nan_boxing_pointer.cpp b/test/nan_boxing_pointer.cpp
index aeef00482..d4fadf233 100644
--- a/test/nan_boxing_pointer.cpp
+++ b/test/nan_boxing_pointer.cpp
@@ -130,29 +130,29 @@ auto main() -> int
   }
 
   {
-    let x = make<std::uint32_t>(static_cast<std::uint32_t>(1)),
-        y = make<std::uint32_t>(static_cast<std::uint32_t>(2));
+    let x = make(static_cast<std::int32_t>(1)),
+        y = make(static_cast<std::int32_t>(2));
 
     // PRINT(demangle(x.type()));
     // PRINT(demangle(y.type()));
 
-    assert(x.is<std::uint32_t>());
-    assert(y.is<std::uint32_t>());
+    assert(x.is<std::int32_t>());
+    assert(y.is<std::int32_t>());
 
     let const pare = cons(x, y);
 
     PRINT(demangle(pare.as<pair>().first.type()));
     PRINT(demangle(pare.as<pair>().second.type()));
 
-    assert(pare.as<pair>().first.is<std::uint32_t>());
-    assert(pare.as<pair>().first.as<std::uint32_t>() == 1);
-    assert(pare.as<pair>().second.is<std::uint32_t>());
-    assert(pare.as<pair>().second.as<std::uint32_t>() == 2);
+    assert(pare.as<pair>().first.is<std::int32_t>());
+    assert(pare.as<pair>().first.as<std::int32_t>() == 1);
+    assert(pare.as<pair>().second.is<std::int32_t>());
+    assert(pare.as<pair>().second.as<std::int32_t>() == 2);
 
-    assert(car(pare).is<std::uint32_t>());
-    assert(car(pare).as<std::uint32_t>() == 1);
-    assert(cdr(pare).is<std::uint32_t>());
-    assert(cdr(pare).as<std::uint32_t>() == 2);
+    assert(car(pare).is<std::int32_t>());
+    assert(car(pare).as<std::int32_t>() == 1);
+    assert(cdr(pare).is<std::int32_t>());
+    assert(cdr(pare).as<std::int32_t>() == 2);
   }
 
   delete p;

From 772beaa605cf576d5a06c3d680e91b673a5e0ecd Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 25 Feb 2024 04:06:36 +0900
Subject: [PATCH 06/40] Cleanup class template `simple_allocator`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                  |  6 +--
 VERSION                                    |  2 +-
 include/meevax/memory/simple_allocator.hpp | 57 ++++++++++------------
 3 files changed, 30 insertions(+), 35 deletions(-)

diff --git a/README.md b/README.md
index 3768fde35..adae04a98 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.124_amd64.deb
+sudo apt install build/meevax_0.5.125_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.124.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.125.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.124_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.125_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index d21b1e44b..48cb90656 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.124
+0.5.125
diff --git a/include/meevax/memory/simple_allocator.hpp b/include/meevax/memory/simple_allocator.hpp
index 9acba8314..16fc619b5 100644
--- a/include/meevax/memory/simple_allocator.hpp
+++ b/include/meevax/memory/simple_allocator.hpp
@@ -17,8 +17,6 @@
 #ifndef INCLUDED_MEEVAX_MEMORY_SIMPLE_ALLOCATOR_HPP
 #define INCLUDED_MEEVAX_MEMORY_SIMPLE_ALLOCATOR_HPP
 
-#include <algorithm> // std::max
-#include <array>
 #include <cstddef>
 #include <cstdint>
 #include <type_traits>
@@ -28,48 +26,47 @@ namespace meevax
 {
 inline namespace memory
 {
-template <typename T, typename Capacity = std::integral_constant<std::size_t, 1024>>
+constexpr auto page_size = 4096;
+
+/*
+   Simple Segregated Storage Allocator
+*/
+template <typename T, typename Capacity = std::integral_constant<std::size_t, page_size / alignof(std::conditional_t<std::is_void_v<T>, int, T>)>>
 class simple_allocator
 {
   struct alignas(T) chunk
   {
-    chunk * next;
+    chunk * tail;
   };
 
-  class chunks
+  struct block
   {
     static constexpr auto chunk_size = std::max(sizeof(T), sizeof(chunk));
 
-    std::array<std::uint8_t, chunk_size * Capacity::value> data;
+    std::uint8_t data[chunk_size * Capacity::value] = {};
 
     std::size_t size = Capacity::value;
 
-  public:
-    chunks * const next;
+    block * const tail;
 
-    explicit constexpr chunks(chunks * next = nullptr)
-      : next { next }
+    explicit constexpr block(block * tail = nullptr)
+      : tail { tail }
     {}
 
-    ~chunks()
+    ~block()
     {
-      delete next;
-    }
-
-    auto remaining() const noexcept
-    {
-      return size;
+      delete tail;
     }
 
     auto pop()
     {
-      return reinterpret_cast<value_type *>(std::addressof(data[chunk_size * --size]));
+      return data + chunk_size * --size;
     }
   };
 
-  chunk * recycled_chunk = nullptr;
+  chunk * free_list = nullptr;
 
-  chunks * fresh_chunks;
+  block * free_space;
 
 public:
   using value_type = T;
@@ -83,7 +80,7 @@ class simple_allocator
   using is_always_equal = std::false_type;
 
   explicit simple_allocator()
-    : fresh_chunks { new chunks() }
+    : free_space { new block() }
   {}
 
   simple_allocator(simple_allocator &&) = delete;
@@ -92,7 +89,7 @@ class simple_allocator
 
   ~simple_allocator()
   {
-    delete fresh_chunks;
+    delete free_space;
   }
 
   auto operator =(simple_allocator &&) -> simple_allocator & = delete;
@@ -101,27 +98,25 @@ class simple_allocator
 
   auto allocate(size_type = 1)
   {
-    if (recycled_chunk)
+    if (free_list)
     {
-      return reinterpret_cast<value_type *>(std::exchange(recycled_chunk, recycled_chunk->next));
+      return reinterpret_cast<value_type *>(std::exchange(free_list, free_list->tail));
     }
     else
     {
-      assert(fresh_chunks);
-
-      if (not (*fresh_chunks).remaining())
+      if (not free_space->size)
       {
-        fresh_chunks = new chunks(fresh_chunks);
+        free_space = new block(free_space);
       }
 
-      return (*fresh_chunks).pop();
+      return reinterpret_cast<value_type *>(free_space->pop());
     }
   }
 
   auto deallocate(value_type * p, size_type = 1) -> void
   {
-    reinterpret_cast<chunk *>(p)->next = recycled_chunk;
-    recycled_chunk = reinterpret_cast<chunk *>(p);
+    reinterpret_cast<chunk *>(p)->tail = free_list;
+    free_list = reinterpret_cast<chunk *>(p);
   }
 };
 } // namespace memory

From 9d2a623fc3842fbcd879831312b88a0309c1b23a Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 2 Mar 2024 09:10:56 +0900
Subject: [PATCH 07/40] Lipsticks

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                             |  6 ++---
 VERSION                               |  2 +-
 include/meevax/kernel/list.hpp        |  2 +-
 include/meevax/kernel/procedure.hpp   |  8 +++++++
 include/meevax/memory/collector.hpp   |  4 ++--
 include/meevax/memory/integer_set.hpp | 32 ++++++++++++++++++---------
 script/cachegrind.sh                  |  4 ++--
 script/massif.sh                      |  2 +-
 src/kernel/list.cpp                   |  2 +-
 src/memory/collector.cpp              |  4 ++--
 10 files changed, 43 insertions(+), 23 deletions(-)

diff --git a/README.md b/README.md
index adae04a98..29440bafa 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.125_amd64.deb
+sudo apt install build/meevax_0.5.126_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.125.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.126.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.125_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.126_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 48cb90656..2614ddd62 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.125
+0.5.126
diff --git a/include/meevax/kernel/list.hpp b/include/meevax/kernel/list.hpp
index fed4695b4..d5db86e3d 100644
--- a/include/meevax/kernel/list.hpp
+++ b/include/meevax/kernel/list.hpp
@@ -93,7 +93,7 @@ inline namespace kernel
 
   auto drop_right(object &, std::size_t) -> object;
 
-  auto length(object const&) -> std::size_t;
+  auto length(object const&) -> std::ptrdiff_t;
 
   auto append(object const&, object const&) -> object;
 
diff --git a/include/meevax/kernel/procedure.hpp b/include/meevax/kernel/procedure.hpp
index 338f06808..ebf5bf507 100644
--- a/include/meevax/kernel/procedure.hpp
+++ b/include/meevax/kernel/procedure.hpp
@@ -29,6 +29,14 @@ inline namespace kernel
   {
     using signature = auto (*)(object &) -> object;
 
+    /*
+       Maybe I should use std::string_view, but I'm worried about the lifetime
+       of the referenced string. The referenced string is either a raw string
+       literal or a std::string held by symbol. In normal use, the lifetime of
+       the primitive_procedure object will not be longer than the lifetime of
+       those strings. However, it is possible to achieve this by manipulating
+       the symbol table directly.
+    */
     std::string const name;
 
     explicit primitive_procedure(std::string const& name)
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index a54e648dc..fb2b9f5f3 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -239,9 +239,9 @@ inline namespace memory
 
     static auto dlsym(std::string const&, void * const) -> void *;
 
-    static auto mark() -> void;
+    static auto mark() noexcept -> void;
 
-    static auto mark(tag * const) -> void;
+    static auto mark(tag * const) noexcept -> void;
 
     static auto sweep() -> void;
   };
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index 1394c74f5..8cab5112a 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -254,17 +254,23 @@ inline namespace memory
 
       auto increment_unless_truthy() noexcept
       {
-        auto i = index / 64;
-        auto j = index % 64;
-
-        for (; i < N / 64; ++i, j = 0)
+        if (auto i = index / 64; i < N/64)
         {
-          if (auto datum = data[i] & (~0ul << j); datum)
+          if (auto datum = data[i] & (~0ul << index % 64); datum)
           {
             index = i * 64 + __builtin_ctzl(datum);
             assert(data[index / 64] & (1ul << index % 64));
             return;
           }
+          else while (++i < N/64)
+          {
+            if (auto datum = data[i]; datum)
+            {
+              index = i * 64 + __builtin_ctzl(datum);
+              assert(data[index / 64] & (1ul << index % 64));
+              return;
+            }
+          }
         }
 
         index = N;
@@ -274,17 +280,23 @@ inline namespace memory
 
       auto decrement_unless_truthy() noexcept
       {
-        auto i = index / 64;
-        auto j = index % 64;
-
-        for (; i < N / 64; --i, j = 63)
+        if (auto i = index / 64; i < N/64)
         {
-          if (auto datum = data[i] & (~0ul >> (63 - j)); datum)
+          if (auto datum = data[i] & (~0ul >> (63 - index % 64)); datum)
           {
             index = i * 64 + (63 - __builtin_clzl(datum));
             assert(data[index / 64] & (1ul << index % 64));
             return;
           }
+          else while (--i < N/64)
+          {
+            if (auto datum = data[i]; datum)
+            {
+              index = i * 64 + (63 - __builtin_clzl(datum));
+              assert(data[index / 64] & (1ul << index % 64));
+              return;
+            }
+          }
         }
 
         index = N;
diff --git a/script/cachegrind.sh b/script/cachegrind.sh
index 14fa2c7e6..afc30341a 100755
--- a/script/cachegrind.sh
+++ b/script/cachegrind.sh
@@ -4,6 +4,6 @@ stem="/tmp/cachegrind"
 
 valgrind --tool=cachegrind \
          --cachegrind-out-file=$stem.out \
-         meevax "$@"
+         "$@"
 
-# cg_annotate /tmp/$stem.out
+cg_annotate $stem.out
diff --git a/script/massif.sh b/script/massif.sh
index 444ad4a0d..49c8a7591 100755
--- a/script/massif.sh
+++ b/script/massif.sh
@@ -7,6 +7,6 @@ valgrind --tool=massif \
          --quiet \
          --stacks=yes \
          --time-unit=B \
-         meevax "$@"
+         "$@"
 
 massif-visualizer $stem.out
diff --git a/src/kernel/list.cpp b/src/kernel/list.cpp
index 2789fc490..e396ec4e6 100644
--- a/src/kernel/list.cpp
+++ b/src/kernel/list.cpp
@@ -246,7 +246,7 @@ inline namespace kernel
     }
   }
 
-  auto length(object const& x) -> std::size_t
+  auto length(object const& x) -> std::ptrdiff_t
   {
     return std::distance(x.begin(), x.end());
   }
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index cd8f91267..892136d35 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -112,7 +112,7 @@ inline namespace memory
     }
   }
 
-  auto collector::mark() -> void
+  auto collector::mark() noexcept -> void
   {
     marker::clear();
 
@@ -144,7 +144,7 @@ inline namespace memory
     }
   }
 
-  auto collector::mark(tag * const tag) -> void
+  auto collector::mark(tag * const tag) noexcept -> void
   {
     assert(tag);
 

From 78bee8940bf239d32a40c11aade94b684a938c87 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 2 Mar 2024 11:29:44 +0900
Subject: [PATCH 08/40] Update to explicitly use `std::nullptr_t` type
 overloading

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 ++--
 VERSION                                       |  2 +-
 include/meevax/kernel/box.hpp                 |  2 +-
 include/meevax/kernel/dynamic_environment.hpp | 20 +++++------
 include/meevax/kernel/include.hpp             |  2 +-
 include/meevax/kernel/library.hpp             |  4 +--
 include/meevax/kernel/list.hpp                | 15 +++++---
 include/meevax/kernel/pair.hpp                |  4 +--
 .../meevax/kernel/syntactic_environment.hpp   | 34 +++++++++----------
 src/kernel/boot.cpp                           |  2 +-
 src/kernel/environment.cpp                    | 10 +++---
 src/kernel/library.cpp                        |  6 ++--
 src/kernel/list.cpp                           | 20 +++++------
 src/kernel/pair.cpp                           |  4 +--
 src/kernel/textual_input_port.cpp             |  4 +--
 test/list.cpp                                 |  6 ++--
 16 files changed, 75 insertions(+), 66 deletions(-)

diff --git a/README.md b/README.md
index 29440bafa..a27542376 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.126_amd64.deb
+sudo apt install build/meevax_0.5.127_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.126.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.127.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.126_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.127_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 2614ddd62..bae6a5b92 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.126
+0.5.127
diff --git a/include/meevax/kernel/box.hpp b/include/meevax/kernel/box.hpp
index 14800a058..9ca99cc62 100644
--- a/include/meevax/kernel/box.hpp
+++ b/include/meevax/kernel/box.hpp
@@ -23,7 +23,7 @@ namespace meevax
 {
 inline namespace kernel
 {
-  struct box : public virtual pair // (value . unit)
+  struct box : public virtual pair // (value . null)
   {
     using pair::pair;
   };
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index 2ca3664f2..14e9f5a1b 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -69,16 +69,16 @@ inline namespace kernel
        `kernel-exception-handler-set!`, it is basically assumed to be set to
        R7RS Scheme's standard procedure `raise`.
     */
-    let static inline raise = unit;
+    let static inline raise = nullptr;
 
     template <typename... Ts>
     auto apply(object const& f, Ts&&... xs) -> object
     {
       s = list(f, list(std::forward<decltype(xs)>(xs)...));
-      e = unit;
+      e = nullptr;
       c = list(make(instruction::call),
                make(instruction::stop));
-      d = unit;
+      d = nullptr;
 
       return run();
     }
@@ -283,7 +283,7 @@ inline namespace kernel
             d = cons(cddr(s), e, cdr(c), d);
             c = car(callee);
             e = cons(cadr(s), cdr(callee));
-            s = unit;
+            s = nullptr;
             goto fetch;
           }
           else if (callee.is_also<primitive_procedure>()) /* -------------------
@@ -333,7 +333,7 @@ inline namespace kernel
             assert(tail(c, 1).template is<null>());
             c = car(callee);
             e = cons(cadr(s), cdr(callee));
-            s = unit;
+            s = nullptr;
             goto fetch;
           }
           else if (callee.is_also<primitive_procedure>()) /* -------------------
@@ -378,13 +378,13 @@ inline namespace kernel
           *  s e (%dummy . c) d => s (<null> . e) c d
           *
           * ----------------------------------------------------------------- */
-          e = cons(unit, e);
+          e = cons(nullptr, e);
           c = cdr(c);
           goto fetch;
 
         case instruction::tail_letrec: /* --------------------------------------
           *
-          *  (<closure> xs . s) (<unit> . e) (%letrec . c) d => () (set-car! e' xs) c' d
+          *  (<closure> xs . s) (<null> . e) (%letrec . c) d => () (set-car! e' xs) c' d
           *
           *  where <closure> = (c' . e')
           *
@@ -392,12 +392,12 @@ inline namespace kernel
           cadar(s) = cadr(s);
           c = caar(s);
           e = cdar(s);
-          s = unit;
+          s = nullptr;
           goto fetch;
 
         case instruction::letrec: /* -------------------------------------------
           *
-          *  (<closure> xs . s) (<unit> . e) (%letrec . c) d => () (set-car! e' xs) c' (s e c . d)
+          *  (<closure> xs . s) (<null> . e) (%letrec . c) d => () (set-car! e' xs) c' (s e c . d)
           *
           *  where <closure> = (c' . e')
           *
@@ -406,7 +406,7 @@ inline namespace kernel
           d = cons(cddr(s), cdr(e), cdr(c), d);
           c = caar(s);
           e = cdar(s);
-          s = unit;
+          s = nullptr;
           goto fetch;
 
         case instruction::return_: /* ------------------------------------------
diff --git a/include/meevax/kernel/include.hpp b/include/meevax/kernel/include.hpp
index 5f7393851..6b6c1ef50 100644
--- a/include/meevax/kernel/include.hpp
+++ b/include/meevax/kernel/include.hpp
@@ -23,7 +23,7 @@ namespace meevax
 {
 inline namespace kernel
 {
-  auto include(object const&, bool = true, object const& = unit) -> object;
+  auto include(object const&, bool = true, object const& = nullptr) -> object;
 } // namespace kernel
 } // namespace meevax
 
diff --git a/include/meevax/kernel/library.hpp b/include/meevax/kernel/library.hpp
index ce1a56f8e..7d4fd291a 100644
--- a/include/meevax/kernel/library.hpp
+++ b/include/meevax/kernel/library.hpp
@@ -26,9 +26,9 @@ inline namespace kernel
 {
   struct library : public environment
   {
-    let declarations = unit;
+    let declarations = nullptr;
 
-    let export_specs = unit;
+    let export_specs = nullptr;
 
     template <typename F, REQUIRES(std::is_invocable<F, library &>)>
     explicit library(F declare)
diff --git a/include/meevax/kernel/list.hpp b/include/meevax/kernel/list.hpp
index d5db86e3d..afea0468a 100644
--- a/include/meevax/kernel/list.hpp
+++ b/include/meevax/kernel/list.hpp
@@ -26,10 +26,10 @@ inline namespace kernel
 {
   inline auto list = [](auto&&... xs) constexpr
   {
-    return (std::forward<decltype(xs)>(xs) | ... | unit);
+    return (std::forward<decltype(xs)>(xs) | ... | nullptr);
   };
 
-  auto make_list(std::size_t, object const& = unit) -> object;
+  auto make_list(std::size_t, object const& = nullptr) -> object;
 
   auto iota(std::size_t, object const& = e0, object const& = e1) -> object;
 
@@ -110,7 +110,14 @@ inline namespace kernel
   template <typename F>
   auto map(F f, object const& xs) -> object
   {
-    return xs.is<pair>() ? cons(f(car(xs)), map(f, cdr(xs))) : unit;
+    if (xs.is<pair>())
+    {
+      return cons(f(car(xs)), map(f, cdr(xs)));
+    }
+    else
+    {
+      return nullptr;
+    }
   }
 
   auto memq(object const&, object const&) -> object const&;
@@ -141,7 +148,7 @@ inline namespace kernel
     }
     else
     {
-      return unit;
+      return nullptr;
     }
   }
 
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 4b7e902d6..8866048a4 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -134,8 +134,8 @@ inline namespace kernel
 
     constexpr pair() = default;
 
-    template <typename T, typename U = decltype((unit)), REQUIRES(std::is_constructible<std::pair<object, object>, T, U>)>
-    explicit pair(T&& x, U&& y = unit)
+    template <typename T, typename U = std::nullptr_t, REQUIRES(std::is_constructible<std::pair<object, object>, T, U>)>
+    explicit pair(T&& x, U&& y = nullptr)
       : std::pair<object, object> { std::forward<decltype(x)>(x), std::forward<decltype(y)>(y) }
     {}
 
diff --git a/include/meevax/kernel/syntactic_environment.hpp b/include/meevax/kernel/syntactic_environment.hpp
index 28df04225..c7af3065e 100644
--- a/include/meevax/kernel/syntactic_environment.hpp
+++ b/include/meevax/kernel/syntactic_environment.hpp
@@ -51,11 +51,11 @@ inline namespace kernel
                eqv(car(x).template as<syntactic_environment>()
                          .identify(cddr(x),
                                    caar(x),
-                                   unit),
+                                   nullptr),
                    car(y).template as<syntactic_environment>()
                          .identify(cddr(y),
                                    caar(y),
-                                   unit));
+                                   nullptr));
       }
 
       friend auto operator <<(std::ostream & os, syntactic_closure const& datum) -> std::ostream &
@@ -350,7 +350,7 @@ inline namespace kernel
              where <binding specs> = ((<variable 1> <initial 1>) ...
                                       (<variable n> <initial n>))
           */
-          let formals = unit;
+          let formals = nullptr;
 
           let body = sequence;
 
@@ -380,7 +380,7 @@ inline namespace kernel
           }
 
           return compile(cons(cons(rename("lambda"), formals, body),
-                              make_list(length(binding_specs), unit)),
+                              make_list(length(binding_specs), nullptr)),
                          bound_variables,
                          free_variables,
                          continuation,
@@ -701,7 +701,7 @@ inline namespace kernel
         else if (let const head = compile(car(expression), // Head expression or definition
                                           bound_variables,
                                           free_variables,
-                                          unit);
+                                          nullptr);
                  head.is<null>()) // The syntax define-syntax creates a transformer from transformer-spec at compile time and registers it in the global environment. The syntax define-syntax is effectively a compile-time side-effect of the syntax environment and does nothing at run-time.
         {
           return sequence(compile,
@@ -773,7 +773,7 @@ inline namespace kernel
         return compile(cons(cons(rename("lambda"),
                                  map(formal, car(expression)), // <formals>
                                  cdr(expression)), // <body>
-                            unit), // dummy
+                            nullptr), // dummy
                        bound_variables,
                        free_variables,
                        continuation);
@@ -814,7 +814,7 @@ inline namespace kernel
         return compile(cons(cons(rename("lambda"),
                                  formals,
                                  cdr(expression)), // <body>
-                            unit), // dummy
+                            nullptr), // dummy
                        bound_variables,
                        free_variables,
                        continuation);
@@ -901,7 +901,7 @@ inline namespace kernel
       *
       * --------------------------------------------------------------------- */
       {
-        let identity = compile.identify(car(expression), unit, unit);
+        let identity = compile.identify(car(expression), nullptr, nullptr);
 
         cdr(identity) = make<transformer>(Environment().execute(compile(cadr(expression),
                                                                         bound_variables)),
@@ -962,8 +962,8 @@ inline namespace kernel
     using injector = std::function<object (object const&)>;
 
     auto operator ()(object const& expression,
-                     object const& bound_variables = unit, // list of <formals>
-                     object const& free_variables = unit,
+                     object const& bound_variables = nullptr, // list of <formals>
+                     object const& free_variables = nullptr,
                      object const& continuation = list(make(instruction::stop)),
                      bool tail = false) -> object
     {
@@ -976,7 +976,7 @@ inline namespace kernel
       *
       * --------------------------------------------------------------------- */
       {
-        return cons(make(instruction::load_constant), unit, continuation);
+        return cons(make(instruction::load_constant), nullptr, continuation);
       }
       else if (not expression.is<pair>()) /* -----------------------------------
       *
@@ -1084,8 +1084,8 @@ inline namespace kernel
 
     inline auto define(object const& variable, object const& value = undefined) -> void
     {
-      assert(identify(variable, unit, unit).template is<absolute>());
-      cdr(identify(variable, unit, unit)) = value;
+      assert(identify(variable, nullptr, nullptr).template is<absolute>());
+      cdr(identify(variable, nullptr, nullptr)) = value;
     }
 
     template <typename T, typename... Ts>
@@ -1152,7 +1152,7 @@ inline namespace kernel
           return car(variable).as<syntactic_environment>()
                               .identify(cddr(variable),
                                         unify(caar(variable), bound_variables),
-                                        unit);
+                                        nullptr);
         }
         else
         {
@@ -1218,13 +1218,13 @@ inline namespace kernel
              bind("quote-syntax"                   , syntax::quote_syntax                  ),
              bind("set!"                           , syntax::set                           )));
 
-      return make<syntactic_closure>(core_syntactic_environment, cons(unit, make_symbol(variable)));
+      return make<syntactic_closure>(core_syntactic_environment, cons(nullptr, make_symbol(variable)));
     }
 
     inline auto sweep(object const& form,
                       object const& bound_variables,
                       object const& free_variables,
-                      object const& binding_specs = unit) const -> pair
+                      object const& binding_specs = nullptr) const -> pair
     {
       if (form.is<pair>() and car(form).is<pair>())
       {
@@ -1327,7 +1327,7 @@ inline namespace kernel
 
       for (auto offset = std::max(length(a), length(b)) - length(xs); 0 < offset; --offset)
       {
-        xs = cons(unit, xs);
+        xs = cons(nullptr, xs);
       }
 
       return xs;
diff --git a/src/kernel/boot.cpp b/src/kernel/boot.cpp
index 54d8c796b..27aa5674f 100644
--- a/src/kernel/boot.cpp
+++ b/src/kernel/boot.cpp
@@ -1769,7 +1769,7 @@ inline namespace kernel
 
       library.define<procedure>("get-environment-variables", []()
       {
-        let alist = unit;
+        let alist = nullptr;
 
         for (auto iter = environ; *iter; ++iter)
         {
diff --git a/src/kernel/environment.cpp b/src/kernel/environment.cpp
index ef1a4acc9..643e3def5 100644
--- a/src/kernel/environment.cpp
+++ b/src/kernel/environment.cpp
@@ -74,9 +74,9 @@ inline namespace kernel
     */
     if (s or e or c)
     {
-      d = cons(std::exchange(s, unit),
-               std::exchange(e, unit),
-               std::exchange(c, unit), d);
+      d = cons(std::exchange(s, nullptr),
+               std::exchange(e, nullptr),
+               std::exchange(c, nullptr), d);
     }
 
     let const result = execute(optimize(compile(expression)));
@@ -96,7 +96,7 @@ inline namespace kernel
     if (x.is_also<error>())
     {
       x.as<error>().raise(); // NOTE: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84476
-      return unit;
+      return nullptr;
     }
     else
     {
@@ -222,7 +222,7 @@ inline namespace kernel
     {
       assert(immigrant.is<absolute>());
 
-      if (let const& inhabitant = std::as_const(*this).identify(car(immigrant), unit, unit); inhabitant == f or interactive)
+      if (let const& inhabitant = std::as_const(*this).identify(car(immigrant), nullptr, nullptr); inhabitant == f or interactive)
       {
         second = cons(immigrant, second);
       }
diff --git a/src/kernel/library.cpp b/src/kernel/library.cpp
index e60b02995..9725fefa5 100644
--- a/src/kernel/library.cpp
+++ b/src/kernel/library.cpp
@@ -68,7 +68,7 @@ inline namespace kernel
 
   auto library::resolve() -> object
   {
-    if (let const unresolved_declarations = std::exchange(declarations, unit); unresolved_declarations.is<pair>())
+    if (let const unresolved_declarations = std::exchange(declarations, nullptr); unresolved_declarations.is<pair>())
     {
       for (let const& unresolved_declaration : unresolved_declarations)
       {
@@ -85,12 +85,12 @@ inline namespace kernel
                    assert(cadr(export_spec).is_also<identifier>());
                    assert(caddr(export_spec).is_also<identifier>());
                    return make<absolute>(caddr(export_spec),
-                                         cdr(identify(cadr(export_spec), unit, unit)));
+                                         cdr(identify(cadr(export_spec), nullptr, nullptr)));
                  }
                  else
                  {
                    assert(export_spec.is_also<identifier>());
-                   return identify(export_spec, unit, unit);
+                   return identify(export_spec, nullptr, nullptr);
                  }
                },
                export_specs);
diff --git a/src/kernel/list.cpp b/src/kernel/list.cpp
index e396ec4e6..178e141af 100644
--- a/src/kernel/list.cpp
+++ b/src/kernel/list.cpp
@@ -29,7 +29,7 @@ inline namespace kernel
     }
     else
     {
-      return unit;
+      return nullptr;
     }
   }
 
@@ -41,7 +41,7 @@ inline namespace kernel
     }
     else
     {
-      return unit;
+      return nullptr;
     }
   }
 
@@ -146,7 +146,7 @@ inline namespace kernel
     }
     else
     {
-      return unit;
+      return nullptr;
     }
   }
 
@@ -154,12 +154,12 @@ inline namespace kernel
   {
     if (0 < k)
     {
-      cdr(drop(x, k - 1)) = unit;
+      cdr(drop(x, k - 1)) = nullptr;
       return x;
     }
     else
     {
-      return unit;
+      return nullptr;
     }
   }
 
@@ -212,7 +212,7 @@ inline namespace kernel
     }
     else
     {
-      return unit;
+      return nullptr;
     }
   }
 
@@ -229,7 +229,7 @@ inline namespace kernel
     }
     else
     {
-      cdr(x) = unit;
+      cdr(x) = nullptr;
     }
   }
 
@@ -242,7 +242,7 @@ inline namespace kernel
     }
     else
     {
-      return unit;
+      return nullptr;
     }
   }
 
@@ -322,7 +322,7 @@ inline namespace kernel
 
   auto reverse(object const& xs) -> object
   {
-    return reverse(xs, unit);
+    return reverse(xs, nullptr);
   }
 
   auto reverse(object & xs, object const& a) -> object
@@ -343,7 +343,7 @@ inline namespace kernel
 
   auto reverse(object & xs) -> object
   {
-    return reverse(xs, unit);
+    return reverse(xs, nullptr);
   }
 
   auto memq(object const& x, object const& xs) -> object const&
diff --git a/src/kernel/pair.cpp b/src/kernel/pair.cpp
index 2a23c408d..b5993a2b1 100644
--- a/src/kernel/pair.cpp
+++ b/src/kernel/pair.cpp
@@ -20,7 +20,7 @@ namespace meevax
 {
 inline namespace kernel
 {
-  let unit { nullptr };
+  let unit = nullptr;
 
   auto pair::compare(pair const* that) const -> bool
   {
@@ -56,7 +56,7 @@ inline namespace kernel
     {
       os << magenta("(") << car(datum);
 
-      for (let xs = cdr(datum); xs != unit; xs = cdr(xs))
+      for (let xs = cdr(datum); not xs.is<null>(); xs = cdr(xs))
       {
         if (xs.is<pair>())
         {
diff --git a/src/kernel/textual_input_port.cpp b/src/kernel/textual_input_port.cpp
index 54e811a0a..c2010132a 100644
--- a/src/kernel/textual_input_port.cpp
+++ b/src/kernel/textual_input_port.cpp
@@ -285,7 +285,7 @@ inline namespace kernel
               }
               else
               {
-                return unit;
+                return nullptr;
               }
             }
             else
@@ -408,7 +408,7 @@ inline namespace kernel
         }
         catch (std::integral_constant<char, ')'> const&)
         {
-          return unit;
+          return nullptr;
         }
         catch (std::integral_constant<char, '.'> const&)
         {
diff --git a/test/list.cpp b/test/list.cpp
index c67f8911a..3d848fe7b 100644
--- a/test/list.cpp
+++ b/test/list.cpp
@@ -12,7 +12,7 @@ auto main() -> int
       c = make<symbol>("c"),
       d = make<symbol>("d");
 
-  assert(lexical_cast<std::string>(cons(a, unit)) == "(a)");
+  assert(lexical_cast<std::string>(cons(a, nullptr)) == "(a)");
 
   assert(lexical_cast<std::string>(cons(list(a), list(b, c, d))) == "((a) b c d)");
 
@@ -24,7 +24,9 @@ auto main() -> int
 
   assert(lexical_cast<std::string>(list(a, make<exact_integer>(3 + 4), c)) == "(a 7 c)");
 
-  assert(lexical_cast<std::string>(list()) == "()");
+  assert(lexical_cast<std::string>(list()) == "nullptr");
+
+  assert(lexical_cast<std::string>(object(list())) == "()");
 
   assert(lexical_cast<std::string>(xcons(list(b, c), a)) == "(a b c)");
 

From 8afde7ddd288192f8ce6662ade1ee7bd5f2eb2d6 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 2 Mar 2024 13:36:18 +0900
Subject: [PATCH 09/40] Remove class `marker`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 +-
 VERSION                                       |  2 +-
 .../kernel/input_homogeneous_vector_port.hpp  |  9 ++-
 .../meevax/kernel/syntactic_environment.hpp   | 23 ++++---
 include/meevax/memory/collector.hpp           | 24 ++++----
 include/meevax/memory/integer_set.hpp         |  1 -
 include/meevax/memory/marker.hpp              | 60 -------------------
 src/kernel/binary_input_file_port.cpp         |  9 ++-
 src/kernel/boot.cpp                           | 25 ++++++--
 src/kernel/environment.cpp                    |  2 +-
 src/kernel/library.cpp                        |  2 +-
 src/memory/collector.cpp                      | 23 +++----
 src/memory/marker.cpp                         | 35 -----------
 13 files changed, 82 insertions(+), 139 deletions(-)
 delete mode 100644 include/meevax/memory/marker.hpp
 delete mode 100644 src/memory/marker.cpp

diff --git a/README.md b/README.md
index a27542376..0eafac6da 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.127_amd64.deb
+sudo apt install build/meevax_0.5.128_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.127.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.128.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.127_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.128_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index bae6a5b92..0a8ee163b 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.127
+0.5.128
diff --git a/include/meevax/kernel/input_homogeneous_vector_port.hpp b/include/meevax/kernel/input_homogeneous_vector_port.hpp
index e448a3eb9..9903d1922 100644
--- a/include/meevax/kernel/input_homogeneous_vector_port.hpp
+++ b/include/meevax/kernel/input_homogeneous_vector_port.hpp
@@ -79,7 +79,14 @@ inline namespace kernel
 
     auto peek() -> object override
     {
-      return deque.empty() ? eof_object : make<exact_integer>(deque.front());
+      if (deque.empty())
+      {
+        return eof_object;
+      }
+      else
+      {
+        return make<exact_integer>(deque.front());
+      }
     }
   };
 
diff --git a/include/meevax/kernel/syntactic_environment.hpp b/include/meevax/kernel/syntactic_environment.hpp
index c7af3065e..e84330fdf 100644
--- a/include/meevax/kernel/syntactic_environment.hpp
+++ b/include/meevax/kernel/syntactic_environment.hpp
@@ -386,19 +386,26 @@ inline namespace kernel
                          continuation,
                          true);
         }
+        else if (cdr(sequence).template is<null>())
+        {
+          return compile(car(sequence),
+                         bound_variables,
+                         free_variables,
+                         continuation,
+                         true);
+        }
         else
         {
           return compile(car(sequence),
                          bound_variables,
                          free_variables,
-                         cdr(sequence).template is<null>() ? continuation
-                                                           : cons(make(instruction::drop),
-                                                                  body(compile,
-                                                                       cdr(sequence),
-                                                                       bound_variables,
-                                                                       free_variables,
-                                                                       continuation)),
-                         cdr(sequence).template is<null>());
+                         cons(make(instruction::drop),
+                              body(compile,
+                                   cdr(sequence),
+                                   bound_variables,
+                                   free_variables,
+                                   continuation)),
+                         false);
         }
       }
 
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index fb2b9f5f3..ff938a2a6 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -24,7 +24,6 @@
 
 #include <meevax/memory/integer_set.hpp>
 #include <meevax/memory/literal.hpp>
-#include <meevax/memory/marker.hpp>
 
 namespace meevax
 {
@@ -40,34 +39,37 @@ inline namespace memory
   class collector
   {
   public:
-    struct tag : public marker
+    struct tag
     {
-      std::uintptr_t address;
+      bool marked : 1;
 
-      std::size_t size;
+      std::size_t size : 15;
+
+      std::uintptr_t address : 48;
 
       explicit tag(void const* const address, std::size_t size)
-        : address { reinterpret_cast<std::uintptr_t>(address) }
+        : marked  { false }
         , size    { size }
-      {}
+        , address { reinterpret_cast<std::uintptr_t>(address) }
+      {
+        assert(size < (1u << 15));
+      }
 
       virtual ~tag() = default;
 
-      template <typename T = void>
       auto lower_address() const noexcept
       {
-        return reinterpret_cast<T *>(address);
+        return address;
       }
 
-      template <typename T = void>
       auto upper_address() const noexcept
       {
-        return reinterpret_cast<T *>(address + size);
+        return address + size;
       }
 
       auto contains(void const* const data) const noexcept
       {
-        return lower_address() <= data and data < upper_address();
+        return reinterpret_cast<void const*>(lower_address()) <= data and data < reinterpret_cast<void const*>(upper_address());
       }
     };
 
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index 8cab5112a..606690d3f 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -23,7 +23,6 @@
 #include <cstdint>
 #include <iterator>
 #include <limits>
-#include <type_traits>
 
 #include <meevax/bit/bit_cast.hpp>
 #include <meevax/bit/log2.hpp>
diff --git a/include/meevax/memory/marker.hpp b/include/meevax/memory/marker.hpp
deleted file mode 100644
index 766dddad1..000000000
--- a/include/meevax/memory/marker.hpp
+++ /dev/null
@@ -1,60 +0,0 @@
-/*
-   Copyright 2018-2023 Tatsuya Yamasaki.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-#ifndef INCLUDED_MEEVAX_MEMORY_MARKER_HPP
-#define INCLUDED_MEEVAX_MEMORY_MARKER_HPP
-
-namespace meevax
-{
-inline namespace memory
-{
-  class marker
-  {
-    static inline std::size_t phase;
-
-    std::size_t value;
-
-  public:
-    struct initializer
-    {
-      explicit initializer();
-    };
-
-    marker() noexcept
-      : value { phase }
-    {}
-
-    auto mark() noexcept
-    {
-      value = phase;
-    }
-
-    auto marked() const noexcept
-    {
-      return value == phase;
-    }
-
-    static auto clear() noexcept
-    {
-      ++phase;
-    }
-  };
-
-  static marker::initializer initializer;
-} // namespace memory
-} // namespace meevax
-
-#endif // INCLUDED_MEEVAX_MEMORY_MARKER_HPP
diff --git a/src/kernel/binary_input_file_port.cpp b/src/kernel/binary_input_file_port.cpp
index 7172b3d7f..4a667af3c 100644
--- a/src/kernel/binary_input_file_port.cpp
+++ b/src/kernel/binary_input_file_port.cpp
@@ -64,7 +64,14 @@ inline namespace kernel
 
   auto binary_input_file_port::peek() -> object
   {
-    return get_ready() ? make<exact_integer>(ifstream.peek()) : eof_object;
+    if (get_ready())
+    {
+      return make<exact_integer>(ifstream.peek());
+    }
+    else
+    {
+      return eof_object;
+    }
   }
 
   auto operator <<(std::ostream & output, binary_input_file_port const& datum) -> std::ostream &
diff --git a/src/kernel/boot.cpp b/src/kernel/boot.cpp
index 27aa5674f..5de22f54e 100644
--- a/src/kernel/boot.cpp
+++ b/src/kernel/boot.cpp
@@ -207,10 +207,16 @@ inline namespace kernel
         return car(xs).as<character>().property().is_lower_case();
       });
 
-      library.define<procedure>("digit-value", [](let const& xs)
+      library.define<procedure>("digit-value", [](let const& xs) -> object
       {
-        auto digit_value = car(xs).as<character>().digit_value();
-        return digit_value ? make<exact_integer>(*digit_value) : f;
+        if (auto digit_value = car(xs).as<character>().digit_value(); digit_value)
+        {
+          return make<exact_integer>(*digit_value);
+        }
+        else
+        {
+          return f;
+        }
       });
 
       library.define<procedure>("char->integer", [](let const& xs)
@@ -637,9 +643,16 @@ inline namespace kernel
         return make<exact_integer>(length(car(xs)));
       });
 
-      library.define<procedure>("length+", [](let const& xs)
+      library.define<procedure>("length+", [](let const& xs) -> object
       {
-        return is_circular_list(car(xs)) ? f : make<exact_integer>(length(car(xs)));
+        if (is_circular_list(car(xs)))
+        {
+          return f;
+        }
+        else
+        {
+          return make<exact_integer>(length(car(xs)));
+        }
       });
 
       library.define<procedure>("append", [](let const& xs)
@@ -1755,7 +1768,7 @@ inline namespace kernel
 
     define<library>("(meevax system)", [](library & library)
     {
-      library.define<procedure>("get-environment-variable", [](let const& xs)
+      library.define<procedure>("get-environment-variable", [](let const& xs) -> object
       {
         if (auto s = std::getenv(static_cast<std::string>(car(xs).as<string>()).c_str()))
         {
diff --git a/src/kernel/environment.cpp b/src/kernel/environment.cpp
index 643e3def5..9f8c149c5 100644
--- a/src/kernel/environment.cpp
+++ b/src/kernel/environment.cpp
@@ -184,7 +184,7 @@ inline namespace kernel
       {
         return [=](let const& renamings)
         {
-          return map([&](let const& identity)
+          return map([&](let const& identity) -> object
                      {
                        assert(identity.is<absolute>());
                        assert(car(identity).is_also<identifier>());
diff --git a/src/kernel/library.cpp b/src/kernel/library.cpp
index 9725fefa5..e5c51d818 100644
--- a/src/kernel/library.cpp
+++ b/src/kernel/library.cpp
@@ -76,7 +76,7 @@ inline namespace kernel
       }
     }
 
-    return map([this](let const& export_spec)
+    return map([this](let const& export_spec) -> object
                {
                  if (export_spec.is<pair>())
                  {
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index 892136d35..f0c23b37d 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -114,8 +114,6 @@ inline namespace memory
 
   auto collector::mark() noexcept -> void
   {
-    marker::clear();
-
     auto is_root_object = [begin = tags.begin()](mutator * given)
     {
       /*
@@ -137,7 +135,7 @@ inline namespace memory
       assert(mutator);
       assert(mutator->object);
 
-      if (not mutator->object->marked() and is_root_object(mutator))
+      if (not mutator->object->marked and is_root_object(mutator))
       {
         mark(mutator->object);
       }
@@ -148,16 +146,17 @@ inline namespace memory
   {
     assert(tag);
 
-    if (not tag->marked())
+    if (not tag->marked)
     {
-      tag->mark();
+      tag->marked = true;
 
-      const auto lower_address = tag->lower_address<mutator>();
-      const auto upper_address = tag->upper_address<mutator>();
+      const auto lower_address = reinterpret_cast<mutator *>(tag->lower_address());
+      const auto upper_address = reinterpret_cast<mutator *>(tag->upper_address());
 
-      for (auto iter = mutators.lower_bound(lower_address); iter != mutators.end() and *iter < upper_address; ++iter)
+      for (auto lower = mutators.lower_bound(lower_address),
+                upper = mutators.lower_bound(upper_address); lower != upper; ++lower)
       {
-        mark((*iter)->object);
+        mark((*lower)->object);
       }
     }
   }
@@ -166,7 +165,11 @@ inline namespace memory
   {
     for (auto&& tag : tags)
     {
-      if (not tag->marked())
+      if (tag->marked)
+      {
+        tag->marked = false;
+      }
+      else
       {
         delete tag;
         tags.erase(tag);
diff --git a/src/memory/marker.cpp b/src/memory/marker.cpp
deleted file mode 100644
index a95f35b1b..000000000
--- a/src/memory/marker.cpp
+++ /dev/null
@@ -1,35 +0,0 @@
-/*
-   Copyright 2018-2023 Tatsuya Yamasaki.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-#include <cstdint>
-
-#include <meevax/memory/marker.hpp>
-
-namespace meevax
-{
-inline namespace memory
-{
-  std::size_t count = 0;
-
-  marker::initializer::initializer()
-  {
-    if (not count++)
-    {
-      phase = {};
-    }
-  }
-} // namespace memory
-} // namespace meevax

From f1e77b8ac624a5ed43a633aefabad97656379f64 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 3 Mar 2024 19:51:32 +0900
Subject: [PATCH 10/40] Reduce wasteful copy constructs of `gc_pointer`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 ++---
 VERSION                                       |  2 +-
 include/meevax/kernel/dynamic_environment.hpp |  4 +--
 include/meevax/kernel/pair.hpp                |  6 ++---
 include/meevax/memory/collector.hpp           | 14 +++++-----
 include/meevax/memory/gc_pointer.hpp          |  6 +++++
 .../meevax/memory/heterogeneous_pointer.hpp   |  2 --
 src/kernel/comparator.cpp                     |  8 +++---
 src/kernel/list.cpp                           | 26 +++++++------------
 9 files changed, 35 insertions(+), 39 deletions(-)

diff --git a/README.md b/README.md
index 0eafac6da..ab250aef8 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.128_amd64.deb
+sudo apt install build/meevax_0.5.129_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.128.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.129.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.128_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.129_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 0a8ee163b..bc9cdac21 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.128
+0.5.129
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index 14e9f5a1b..a2a6957de 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -72,7 +72,7 @@ inline namespace kernel
     let static inline raise = nullptr;
 
     template <typename... Ts>
-    auto apply(object const& f, Ts&&... xs) -> object
+    auto apply(object const& f, Ts&&... xs) -> decltype(auto)
     {
       s = list(f, list(std::forward<decltype(xs)>(xs)...));
       e = nullptr;
@@ -95,7 +95,7 @@ inline namespace kernel
       return run();
     }
 
-    auto reraise(object const& x) -> object
+    auto reraise(object const& x) -> decltype(auto)
     {
       return raise.is<null>() ? throw x : apply(raise, x);
     }
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 8866048a4..5f731bae2 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -37,14 +37,14 @@ inline namespace kernel
   template <typename T,
             typename Allocator = collector::default_allocator<void>,
             typename... Ts>
-  auto make(Ts&&... xs) -> object
+  auto make(Ts&&... xs) -> decltype(auto)
   {
     return object::make<T, Allocator>(std::forward<decltype(xs)>(xs)...);
   }
 
   template <typename T,
             typename Allocator = collector::default_allocator<void>>
-  auto make(T&& x) -> object
+  auto make(T&& x) -> decltype(auto)
   {
     return object::make<std::decay_t<T>, Allocator>(std::forward<decltype(x)>(x));
   }
@@ -139,8 +139,6 @@ inline namespace kernel
       : std::pair<object, object> { std::forward<decltype(x)>(x), std::forward<decltype(y)>(y) }
     {}
 
-    virtual ~pair() = default;
-
     virtual auto compare(pair const*) const -> bool;
 
     virtual auto type() const noexcept -> std::type_info const&;
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index ff938a2a6..d2fd2a1eb 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -100,12 +100,12 @@ inline namespace memory
       */
       static inline auto allocator = allocator_type();
 
-      T body;
+      T value;
 
       template <typename... Ts>
       explicit tagged(Ts&&... xs)
-        : tag  { std::addressof(body), sizeof(T) }
-        , body { std::forward<decltype(xs)>(xs)... }
+        : tag   { std::addressof(value), sizeof(T) }
+        , value { std::forward<decltype(xs)>(xs)... }
       {}
 
       ~tagged() override = default;
@@ -128,7 +128,7 @@ inline namespace memory
     protected:
       tag * object = nullptr;
 
-      explicit constexpr mutator() = default;
+      constexpr mutator() = default;
 
       explicit mutator(tag * object) noexcept
         : object { object }
@@ -165,7 +165,7 @@ inline namespace memory
         {
           return nullptr;
         }
-        else if (cache->contains(data)) // Heuristic-based optimization.
+        else if (cache->contains(data))
         {
           return cache;
         }
@@ -183,7 +183,7 @@ inline namespace memory
     template <typename... Ts>
     using default_allocator = std::allocator<Ts...>;
 
-  protected:
+  private:
     static inline tag * cache = nullptr;
 
     static inline integer_set<tag *, 16, 16, 16> tags {};
@@ -221,7 +221,7 @@ inline namespace memory
       {
         tags.insert(cache = data);
 
-        return std::addressof(data->body);
+        return std::addressof(data->value);
       }
       else
       {
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index c737a9398..3e179718e 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -86,6 +86,12 @@ inline namespace memory
       pointer::reset();
       collector::mutator::reset();
     }
+
+    template <typename T, typename Allocator, typename... Us>
+    static auto make(Us&&... xs) -> gc_pointer
+    {
+      return pointer::template make<T, Allocator>(std::forward<decltype(xs)>(xs)...);
+    }
   };
 } // namespace memory
 } // namespace meevax
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
index 96f7f4b79..da2fe35f9 100644
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ b/include/meevax/memory/heterogeneous_pointer.hpp
@@ -48,8 +48,6 @@ inline namespace memory
           }
       {}
 
-      ~binder() override = default;
-
       auto compare([[maybe_unused]] Top const* top) const -> bool override
       {
         if constexpr (is_equality_comparable_v<Bound const&>)
diff --git a/src/kernel/comparator.cpp b/src/kernel/comparator.cpp
index 59825f240..207027033 100644
--- a/src/kernel/comparator.cpp
+++ b/src/kernel/comparator.cpp
@@ -21,7 +21,7 @@ namespace meevax
 {
 inline namespace kernel
 {
-  auto find(object & b) -> object const&
+  auto find(object & b) -> object &
   {
     if (let & x = car(b); x.is<box>())
     {
@@ -41,8 +41,10 @@ inline namespace kernel
     {
       if (auto iterator_y = forest.find(y); iterator_y != forest.end())
       {
-        if (let root_x = find(iterator_x->second),
-                root_y = find(iterator_y->second); eq(root_x, root_y))
+        auto&& root_x = find(iterator_x->second);
+        auto&& root_y = find(iterator_y->second);
+
+        if (eq(root_x, root_y))
         {
           return true;
         }
diff --git a/src/kernel/list.cpp b/src/kernel/list.cpp
index 178e141af..74db185e1 100644
--- a/src/kernel/list.cpp
+++ b/src/kernel/list.cpp
@@ -51,8 +51,8 @@ inline namespace kernel
     {
       if (let const& x1 = cdr(x0); x1.is<pair>())
       {
-        let const& x2 = cdr(x1),
-                   y1 = cdr(y0);
+        let const& x2 = cdr(x1);
+        let const& y1 = cdr(y0);
 
         return not eq(x2, y1) and is_list(x2, y1);
       }
@@ -78,8 +78,8 @@ inline namespace kernel
     {
       if (let const& x1 = cdr(x0); x1.is<pair>())
       {
-        let const& x2 = cdr(x1),
-                   y1 = cdr(y0);
+        let const& x2 = cdr(x1);
+        let const& y1 = cdr(y0);
 
         return eq(x2, y1) or is_circular_list(x2, y1);
       }
@@ -105,8 +105,8 @@ inline namespace kernel
     {
       if (let const& x1 = cdr(x0); x1.is<pair>())
       {
-        let const& x2 = cdr(x1),
-                   y1 = cdr(y0);
+        let const& x2 = cdr(x1);
+        let const& y1 = cdr(y0);
 
         return not eq(x2, y1) and is_dotted_list(x2, y1);
       }
@@ -235,7 +235,7 @@ inline namespace kernel
 
   auto drop_right(object & x, std::size_t k) -> object
   {
-    if (let const y = drop(x, k); y.is<pair>())
+    if (let const& y = drop(x, k); y.is<pair>())
     {
       drop_right(x, cdr(y));
       return x;
@@ -300,11 +300,7 @@ inline namespace kernel
     }
     else
     {
-      let const cdr_x = cdr(x);
-
-      cdr(x) = y;
-
-      return append_reverse(cdr_x, x);
+      return append_reverse(std::exchange(cdr(x), y), x);
     }
   }
 
@@ -333,11 +329,7 @@ inline namespace kernel
     }
     else
     {
-      let tail = cdr(xs);
-
-      cdr(xs) = a;
-
-      return reverse(tail, xs);
+      return reverse(std::exchange(cdr(xs), a), xs);
     }
   }
 

From 7bd5bb6e936dc01647a0c1d269141f885c9ecb63 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Wed, 6 Mar 2024 02:33:14 +0900
Subject: [PATCH 11/40] Remove the code that gives stateful allocator to `make`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 CMakeLists.txt                                |  3 +--
 README.md                                     |  6 +++---
 VERSION                                       |  2 +-
 include/meevax/kernel/dynamic_environment.hpp | 12 ++----------
 include/meevax/kernel/pair.hpp                |  7 +++----
 include/meevax/memory/collector.hpp           |  2 ++
 test/pair.cpp                                 | 11 -----------
 7 files changed, 12 insertions(+), 31 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index dcd7e9160..f6e4b98c4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,8 +1,7 @@
 cmake_minimum_required(VERSION 3.16.3) # Ubuntu 20.04 LTS default
 
 execute_process(
-  COMMAND cat ${CMAKE_CURRENT_SOURCE_DIR}/VERSION
-  COMMAND tr -d "\n"
+  COMMAND head -c -1 ${CMAKE_CURRENT_SOURCE_DIR}/VERSION
   OUTPUT_VARIABLE CURRENT_VERSION)
 
 project(meevax
diff --git a/README.md b/README.md
index ab250aef8..1b6177264 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.129_amd64.deb
+sudo apt install build/meevax_0.5.130_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.129.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.130.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.129_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.130_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index bc9cdac21..6cdbc5dda 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.129
+0.5.130
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index a2a6957de..58714edc0 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -110,14 +110,6 @@ inline namespace kernel
       fetch:
         assert(c);
 
-        if constexpr (false)
-        {
-          std::cerr << faint("; s = ") << s << "\n"
-                    << faint("; e = ") << e << "\n"
-                    << faint("; c = ") << c << "\n"
-                    << faint("; d = ") << d << "\n" << std::endl;
-        }
-
         switch (car(c).template as<instruction>())
         {
         case instruction::load_absolute: /* ------------------------------------
@@ -214,7 +206,7 @@ inline namespace kernel
           *  where <closure> = (c' . e)
           *
           * ----------------------------------------------------------------- */
-          s = cons(make<closure, simple_allocator<void>>(cadr(c), e), s);
+          s = cons(make<closure>(cadr(c), e), s);
           c = cddr(c);
           goto fetch;
 
@@ -225,7 +217,7 @@ inline namespace kernel
           *  where <continuation> = (s e c' . d)
           *
           * ----------------------------------------------------------------- */
-          s = cons(list(make<continuation, simple_allocator<void>>(s, cons(e, cons(cadr(c), d)))), s);
+          s = cons(list(make<continuation>(s, cons(e, cons(cadr(c), d)))), s);
           c = cddr(c);
           goto fetch;
 
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 5f731bae2..11c778fee 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -20,7 +20,6 @@
 #include <meevax/kernel/character.hpp>
 #include <meevax/kernel/instruction.hpp>
 #include <meevax/memory/gc_pointer.hpp>
-#include <meevax/memory/simple_allocator.hpp>
 
 namespace meevax
 {
@@ -28,7 +27,7 @@ inline namespace kernel
 {
   struct pair;
 
-  using object = gc_pointer<pair, bool, std::int32_t, float, character, instruction>;
+  using object = gc_pointer<pair, bool, int, float, character, instruction>;
 
   using let = object;
 
@@ -181,8 +180,8 @@ inline namespace kernel
   template <typename T, typename U, REQUIRES(std::is_constructible<pair, T, U>)>
   auto operator |(T&& x, U&& y) -> decltype(auto)
   {
-    return make<pair, simple_allocator<void>>(std::forward<decltype(x)>(x),
-                                              std::forward<decltype(y)>(y));
+    return make<pair>(std::forward<decltype(x)>(x),
+                      std::forward<decltype(y)>(y));
   }
 
   inline auto cons = [](auto&&... xs) constexpr
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index d2fd2a1eb..d80beae15 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -98,6 +98,8 @@ inline namespace memory
          and releases the pool in the allocator destructor, will cause
          problems.
       */
+      static_assert(allocator_type::is_always_equal::value);
+
       static inline auto allocator = allocator_type();
 
       T value;
diff --git a/test/pair.cpp b/test/pair.cpp
index b0e969d17..c2f07004c 100644
--- a/test/pair.cpp
+++ b/test/pair.cpp
@@ -2,7 +2,6 @@
 
 #include <cassert>
 #include <meevax/kernel/environment.hpp>
-#include <meevax/memory/simple_allocator.hpp>
 
 auto main() -> int
 {
@@ -12,15 +11,5 @@ auto main() -> int
 
   assert((make<pair, std::allocator<void>>().is<pair>()));
 
-  assert((make<pair, meevax::simple_allocator<void>>().is<pair>()));
-
-  /*
-     Without this explicit call to default_collector.clear(), illegal memory
-     access by the destructor of the collector will occur for objects allocated
-     by allocators other than std::allocator. See the comments attached to
-     collector::tagged::allocator for a detailed description of this problem.
-  */
-  default_collector.clear();
-
   return EXIT_SUCCESS;
 }

From e02ef5e87c4f5c943f13e54fea7607a90f36f51b Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Wed, 6 Mar 2024 05:19:02 +0900
Subject: [PATCH 12/40] Update `collector` to support stateful custom allocator

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 +--
 VERSION                                       |  2 +-
 include/meevax/kernel/dynamic_environment.hpp |  4 +-
 include/meevax/kernel/pair.hpp                |  4 +-
 include/meevax/memory/collector.hpp           | 44 +++++++++----------
 src/memory/collector.cpp                      |  6 +--
 6 files changed, 31 insertions(+), 35 deletions(-)

diff --git a/README.md b/README.md
index 1b6177264..f25fcc266 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.130_amd64.deb
+sudo apt install build/meevax_0.5.131_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.130.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.131.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.130_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.131_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 6cdbc5dda..6db3b96b3 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.130
+0.5.131
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index 58714edc0..513b1eba7 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -206,7 +206,7 @@ inline namespace kernel
           *  where <closure> = (c' . e)
           *
           * ----------------------------------------------------------------- */
-          s = cons(make<closure>(cadr(c), e), s);
+          s = cons(make<closure, simple_allocator<void>>(cadr(c), e), s);
           c = cddr(c);
           goto fetch;
 
@@ -217,7 +217,7 @@ inline namespace kernel
           *  where <continuation> = (s e c' . d)
           *
           * ----------------------------------------------------------------- */
-          s = cons(list(make<continuation>(s, cons(e, cons(cadr(c), d)))), s);
+          s = cons(list(make<continuation, simple_allocator<void>>(s, cons(e, cons(cadr(c), d)))), s);
           c = cddr(c);
           goto fetch;
 
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 11c778fee..34344d818 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -180,8 +180,8 @@ inline namespace kernel
   template <typename T, typename U, REQUIRES(std::is_constructible<pair, T, U>)>
   auto operator |(T&& x, U&& y) -> decltype(auto)
   {
-    return make<pair>(std::forward<decltype(x)>(x),
-                      std::forward<decltype(y)>(y));
+    return make<pair, simple_allocator<void>>(std::forward<decltype(x)>(x),
+                                              std::forward<decltype(y)>(y));
   }
 
   inline auto cons = [](auto&&... xs) constexpr
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index d80beae15..725f251c0 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -24,6 +24,7 @@
 
 #include <meevax/memory/integer_set.hpp>
 #include <meevax/memory/literal.hpp>
+#include <meevax/memory/simple_allocator.hpp>
 
 namespace meevax
 {
@@ -73,32 +74,26 @@ inline namespace memory
       }
     };
 
+    static inline auto cleared = false;
+
     template <typename T, typename AllocatorTraits>
     struct tagged : public tag
     {
-      using allocator_type = typename AllocatorTraits::template rebind_alloc<tagged<T, AllocatorTraits>>;
-
-      using pointer = typename std::allocator_traits<allocator_type>::pointer;
-
-      /*
-         Support for custom allocators is incomplete. Because the allocator is
-         templated and held as a static data member, this allocator may be
-         constructed after the collector and destructed before the collector.
-         (See "Static Initialization/Destruction Order Fiasco.") In that case,
-         illegal memory accesses will occur because the allocator corresponding
-         to a particular type has already been destructed at the time
-         collector::clear() is called within collector::~collector().
-
-         The problem is currently not occurring because the lifetime of the
-         storage allocated by std::allocator is independent of the lifetime of
-         the std::allocator type object. Conversely, if there is a relationship
-         between the storage allocated by the allocator object and the lifetime
-         of the allocator object, a problem will occur. For example, a memory
-         pool allocator, which allocates the pool in the allocator constructor
-         and releases the pool in the allocator destructor, will cause
-         problems.
-      */
-      static_assert(allocator_type::is_always_equal::value);
+      struct allocator_type : public AllocatorTraits::template rebind_alloc<tagged<T, AllocatorTraits>>
+      {
+        ~allocator_type()
+        {
+          /*
+             Execute clear before any static allocator is destroyed. Otherwise,
+             when the destructor of the collector executes clear, the collector
+             may touch the freed memory of the stateful allocator.
+          */
+          if (not std::exchange(cleared, true))
+          {
+            clear();
+          }
+        }
+      };
 
       static inline auto allocator = allocator_type();
 
@@ -119,6 +114,7 @@ inline namespace memory
 
       auto operator delete(void * data) noexcept -> void
       {
+        using pointer = typename std::allocator_traits<allocator_type>::pointer;
         allocator.deallocate(reinterpret_cast<pointer>(data), 1);
       }
     };
@@ -250,7 +246,7 @@ inline namespace memory
     static auto sweep() -> void;
   };
 
-  extern collector default_collector;
+  static collector default_collector {};
 } // namespace memory
 } // namespace meevax
 
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index f0c23b37d..8b93fde75 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -29,13 +29,13 @@ namespace meevax
 {
 inline namespace memory
 {
-  collector default_collector {};
-
   static auto reference_count = 0;
 
   collector::collector()
   {
-    ++reference_count;
+    if (not reference_count++)
+    {
+    }
   }
 
   collector::~collector()

From 40d407b4f6c7e3311cf28857f7381553fa714e6f Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Thu, 7 Mar 2024 00:24:08 +0900
Subject: [PATCH 13/40] Remove unused template parameters from
 `dynamic_environment`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     | 6 +++---
 VERSION                                       | 2 +-
 include/meevax/kernel/dynamic_environment.hpp | 1 -
 include/meevax/kernel/environment.hpp         | 4 +---
 include/meevax/memory/simple_allocator.hpp    | 4 +---
 src/kernel/environment.cpp                    | 2 --
 6 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index f25fcc266..7c2419896 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.131_amd64.deb
+sudo apt install build/meevax_0.5.132_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.131.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.132.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.131_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.132_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 6db3b96b3..a294f9f71 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.131
+0.5.132
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index 513b1eba7..df594807e 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -26,7 +26,6 @@ namespace meevax
 {
 inline namespace kernel
 {
-  template <typename Environment>
   struct dynamic_environment
   {
     /*
diff --git a/include/meevax/kernel/environment.hpp b/include/meevax/kernel/environment.hpp
index 07c62cb80..e3409cf08 100644
--- a/include/meevax/kernel/environment.hpp
+++ b/include/meevax/kernel/environment.hpp
@@ -27,7 +27,7 @@ namespace meevax
 inline namespace kernel
 {
   struct environment : public configurator<environment>
-                     , public dynamic_environment<environment>
+                     , public dynamic_environment
                      , public optimizer
                      , public syntactic_environment<environment>
   {
@@ -44,8 +44,6 @@ inline namespace kernel
 
   extern template struct configurator<environment>;
 
-  extern template struct dynamic_environment<environment>;
-
   extern template struct syntactic_environment<environment>;
 } // namespace kernel
 } // namespace meevax
diff --git a/include/meevax/memory/simple_allocator.hpp b/include/meevax/memory/simple_allocator.hpp
index 16fc619b5..dbc08acfc 100644
--- a/include/meevax/memory/simple_allocator.hpp
+++ b/include/meevax/memory/simple_allocator.hpp
@@ -26,12 +26,10 @@ namespace meevax
 {
 inline namespace memory
 {
-constexpr auto page_size = 4096;
-
 /*
    Simple Segregated Storage Allocator
 */
-template <typename T, typename Capacity = std::integral_constant<std::size_t, page_size / alignof(std::conditional_t<std::is_void_v<T>, int, T>)>>
+template <typename T, typename Capacity = std::integral_constant<std::size_t, 1024>>
 class simple_allocator
 {
   struct alignas(T) chunk
diff --git a/src/kernel/environment.cpp b/src/kernel/environment.cpp
index 9f8c149c5..6f45a99a2 100644
--- a/src/kernel/environment.cpp
+++ b/src/kernel/environment.cpp
@@ -256,8 +256,6 @@ inline namespace kernel
 
   template struct configurator<environment>;
 
-  template struct dynamic_environment<environment>;
-
   template struct syntactic_environment<environment>;
 } // namespace kernel
 } // namespace meevax

From fe162edf72d48942c58c89d8dfcc4fcef48626d3 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Fri, 8 Mar 2024 02:03:56 +0900
Subject: [PATCH 14/40] Move `apply` and `map` into library `(meevax apply)`
 and `(meevax map)`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md       |  6 +++---
 VERSION         |  2 +-
 basis/meevax.ss | 42 ++++++++++++++++++++++++++++++++++++++++++
 basis/r4rs.ss   | 37 +++----------------------------------
 4 files changed, 49 insertions(+), 38 deletions(-)

diff --git a/README.md b/README.md
index 7c2419896..5a7495113 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.132_amd64.deb
+sudo apt install build/meevax_0.5.133_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.132.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.133.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.132_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.133_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index a294f9f71..8c09dab9e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.132
+0.5.133
diff --git a/basis/meevax.ss b/basis/meevax.ss
index 098b20678..914877bf1 100644
--- a/basis/meevax.ss
+++ b/basis/meevax.ss
@@ -98,3 +98,45 @@
                          ((cdr before/after)))
                        (current-dynamic-extents))
              (emergency-exit . xs)))))
+
+(define-library (meevax apply)
+  (import (only (meevax core) define if lambda)
+          (only (meevax list) append null? reverse)
+          (only (meevax pair) car cdr cons))
+
+  (export apply)
+
+  (begin (define (apply f x . xs)
+           (if (null? xs)
+               (f . x)
+               ((lambda (xs)
+                  ((lambda (x)
+                     (f . x))
+                   (append (reverse (cdr xs))
+                           (car xs))))
+                (reverse (cons x xs)))))))
+
+(define-library (meevax map)
+  (import (only (meevax apply) apply)
+          (only (meevax core) define if quote)
+          (only (meevax list) memq null? reverse)
+          (only (meevax pair) car cdr cons))
+
+  (export map)
+
+  (begin (define (map f . xs)
+           (define (map f x a)
+             (if (null? x)
+                 (reverse a)
+                 (map f
+                      (cdr x)
+                      (cons (f (car x)) a))))
+           (define (map* f xs a)
+             (if (memq '() xs)
+                 (reverse a)
+                 (map* f
+                       (map cdr xs '())
+                       (cons (apply f (map car xs '())) a))))
+           (if (null? (cdr xs))
+               (map f (car xs) '())
+               (map* f xs '())))))
diff --git a/basis/r4rs.ss b/basis/r4rs.ss
index 71a31bfff..cd222ccbe 100644
--- a/basis/r4rs.ss
+++ b/basis/r4rs.ss
@@ -35,7 +35,8 @@
 |#
 
 (define-library (scheme r4rs)
-  (import (only (meevax boolean) boolean? not)
+  (import (only (meevax apply) apply)
+          (only (meevax boolean) boolean? not)
           (only (meevax character) char? char=? char<? char>? char<=? char>=? char-ci=? char-ci<? char-ci>? char-ci<=? char-ci>=? char-alphabetic? char-numeric? char-whitespace? char-upper-case? char-lower-case? char->integer integer->char char-upcase char-downcase)
           (only (meevax comparator) eq? eqv? equal?)
           (only (meevax complex) make-rectangular make-polar real-part imag-part magnitude angle)
@@ -44,6 +45,7 @@
           (only (meevax inexact) exp log sqrt sin cos tan asin acos atan)
           (only (meevax list) null? list? list length append reverse list-tail list-ref memq memv assq assv)
           (only (meevax macro-transformer) er-macro-transformer identifier?)
+          (only (meevax map) map)
           (only (meevax number) number? complex? real? rational? integer? exact? inexact? = < > <= >= zero? positive? negative? odd? even? max min + * - / abs quotient remainder modulo gcd lcm numerator denominator floor ceiling truncate round expt exact inexact number->string string->number)
           (only (meevax pair) pair? cons car cdr set-car! set-cdr! caar cadr cdar cddr caaar caadr cadar caddr cdaar cdadr cddar cdddr caaaar caaadr caadar caaddr cadaar cadadr caddar cadddr cdaaar cdaadr cdadar cdaddr cddaar cddadr cdddar cddddr)
           (only (meevax port) input-port? output-port? standard-input-port standard-output-port open-input-file open-output-file close eof-object?)
@@ -183,39 +185,6 @@
                        (else x)))
                (expand (cadr form) 0))))
 
-         (define (every f xs)
-           (if (pair? xs)
-               (and (f (car xs))
-                    (every f (cdr xs)))
-               #t))
-
-         (define (map f x . xs) ; Chibi-Scheme
-           (define (map f x a)
-             (if (pair? x)
-                 (map f
-                      (cdr x)
-                      (cons (f (car x)) a))
-                 (reverse a)))
-           (define (map* f xs a)
-             (if (every pair? xs)
-                 (map* f
-                       (map cdr xs '())
-                       (cons (apply f (map car xs '())) a))
-                 (reverse a)))
-           (if (null? xs)
-               (map f x '())
-               (map* f (cons x xs) '())))
-
-         (define (apply f x . xs) ; Chibi-Scheme
-           (letrec ((apply (lambda (f xs)
-                             (f . xs))))
-             (if (null? xs)
-                 (apply f x)
-                 ((lambda (xs)
-                    (apply f (append (reverse (cdr xs))
-                                     (car xs))))
-                  (reverse (cons x xs))))))
-
          (define-syntax let ; Chibi-Scheme
            (er-macro-transformer
              (lambda (form rename compare)

From b44edbe2e3ee5412ad2dc8afdc3fefbde42f34c1 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Fri, 8 Mar 2024 02:08:47 +0900
Subject: [PATCH 15/40] Update `(srfi 39)` to depend only on the library
 prefixed `(meevax *)`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md        | 6 +++---
 VERSION          | 2 +-
 basis/srfi-39.ss | 5 ++---
 3 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 5a7495113..8f245e2be 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.133_amd64.deb
+sudo apt install build/meevax_0.5.134_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.133.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.134.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.133_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.134_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 8c09dab9e..0bb407333 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.133
+0.5.134
diff --git a/basis/srfi-39.ss b/basis/srfi-39.ss
index 85abb1c21..ec61a2800 100644
--- a/basis/srfi-39.ss
+++ b/basis/srfi-39.ss
@@ -26,9 +26,8 @@
           (only (meevax core) define define-syntax if lambda letrec quote)
           (only (meevax list) null? list append assq)
           (only (meevax macro-transformer) er-macro-transformer)
-          (only (meevax pair) cons car cdr cadr cddr set-car! set-cdr!)
-          (only (scheme r5rs) map)
-          )
+          (only (meevax map) map)
+          (only (meevax pair) cons car cdr cadr cddr set-car! set-cdr!))
 
   (export make-parameter parameterize)
 

From 258efd1fda336ff1e857edd43af41a7ed14aaf1d Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 9 Mar 2024 14:36:06 +0900
Subject: [PATCH 16/40] Update `(scheme r4rs)` to use `(srfi 39)` to define
 some procedures

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md     |  6 +++---
 VERSION       |  2 +-
 basis/r4rs.ss | 26 +++++++++++---------------
 basis/r7rs.ss | 45 +++++----------------------------------------
 4 files changed, 20 insertions(+), 59 deletions(-)

diff --git a/README.md b/README.md
index 8f245e2be..7487048e3 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.134_amd64.deb
+sudo apt install build/meevax_0.5.135_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.134.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.135.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.134_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.135_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 0bb407333..da9c7dd0e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.134
+0.5.135
diff --git a/basis/r4rs.ss b/basis/r4rs.ss
index cd222ccbe..499cbf63c 100644
--- a/basis/r4rs.ss
+++ b/basis/r4rs.ss
@@ -53,9 +53,10 @@
           (only (meevax string) string? make-string string string-length string-ref string-set! string=? string<? string>? string<=? string>=? string-ci=? string-ci<? string-ci>? string-ci<=? string-ci>=? string-append string->list list->string string-copy string-fill!)
           (only (meevax symbol) symbol? symbol->string string->symbol)
           (only (meevax vector) vector? make-vector vector vector-length vector-ref vector-set! vector->list list->vector vector-fill!)
-          (prefix (only (meevax environment) load) %)
           (prefix (meevax read) %)
           (prefix (meevax write) %)
+          (prefix (only (meevax environment) load) %)
+          (only (srfi 39) make-parameter parameterize)
           (only (srfi 45) delay force))
 
   (export quote lambda if set! cond case and or let let* letrec begin do delay
@@ -279,8 +280,7 @@
                        (else (+ 1 fx)))))
              (cond ((< y x)
                     (simplest-rational y x))
-                   ((not (< x y))
-                    (if (rational? x) x (error x)))
+                   ((not (< x y)) x)
                    ((positive? x)
                     (simplest-rational-internal x y))
                    ((negative? x)
@@ -317,25 +317,21 @@
                result))
            (call-with-output-port (open-output-file path) f))
 
-         (define %current-input-port (standard-input-port))
-
-         (define (current-input-port) %current-input-port)
-
-         (define %current-output-port (standard-output-port))
+         (define current-input-port
+           (make-parameter (standard-input-port)))
 
-         (define (current-output-port) %current-output-port)
+         (define current-output-port
+           (make-parameter (standard-output-port)))
 
          (define (with-input-from-file path thunk)
-           (let ((previous-input-port (current-input-port)))
-             (set! %current-input-port (open-input-file path))
+           (parameterize ((current-input-port (open-input-file path)))
              (thunk)
-             (set! %current-input-port previous-input-port)))
+             (close-input-port (current-input-port))))
 
          (define (with-output-to-file path thunk)
-           (let ((previous-output-port (current-output-port)))
-             (set! %current-output-port (open-output-file path))
+           (parameterize ((current-output-port (open-output-file path)))
              (thunk)
-             (set! %current-output-port previous-output-port)))
+             (close-output-port (current-output-port))))
 
          (define close-input-port close)
 
diff --git a/basis/r7rs.ss b/basis/r7rs.ss
index 22353c49b..7b5d562d4 100644
--- a/basis/r7rs.ss
+++ b/basis/r7rs.ss
@@ -1,15 +1,15 @@
 (define-library (scheme base)
   (import (only (meevax core) include include-case-insensitive)
           (only (meevax error) error-object? read-error? file-error?)
-          (only (meevax macro-transformer) er-macro-transformer)
           (only (meevax list) make-list list-copy)
+          (only (meevax macro-transformer) er-macro-transformer)
           (only (meevax number) exact-integer? exact-integer-square-root)
           (only (meevax port) binary-port? eof-object flush get-output-u8vector open-input-u8vector open-output-u8vector open? port? standard-error-port standard-input-port standard-output-port textual-port?)
-          (prefix (meevax read) %)
           (only (meevax string) string-copy!)
           (only (meevax vector homogeneous) u8vector? make-u8vector u8vector u8vector-length u8vector-ref u8vector-set! u8vector-copy u8vector-copy! u8vector-append u8vector->string string->u8vector)
           (only (meevax vector) vector-append vector-copy vector-copy! vector->string string->vector)
           (only (meevax version) features)
+          (prefix (meevax read) %)
           (prefix (meevax write) %)
           (scheme r5rs)
           (srfi 0)
@@ -250,32 +250,8 @@
 
          (define output-port-open? open?)
 
-         (define current-input-port
-           (make-parameter (standard-input-port)
-             (lambda (x)
-               (cond ((not (input-port? x))
-                      (error "not an input-port" x))
-                     ((not (input-port-open? x))
-                      (error "not an opened input-port" x))
-                     (else x)))))
-
-         (define current-output-port
-           (make-parameter (standard-output-port)
-             (lambda (x)
-               (cond ((not (output-port? x))
-                      (error "not an output-port" x))
-                     ((not (output-port-open? x))
-                      (error "not an opened output-port" x))
-                     (else x)))))
-
          (define current-error-port
-           (make-parameter (standard-error-port)
-             (lambda (x)
-               (cond ((not (output-port? x))
-                      (error "not an output-port" x))
-                     ((not (output-port-open? x))
-                      (error "not an opened output-port" x))
-                     (else x)))))
+           (make-parameter (standard-error-port)))
 
          (define (close-port x)
            (cond ((input-port? x) (close-input-port x))
@@ -440,21 +416,10 @@
   (import (only (meevax file) delete-file file-exists?)
           (only (meevax port) open-binary-input-file open-binary-output-file)
           (only (scheme base) close-input-port close-output-port current-input-port current-output-port define parameterize)
-          (only (scheme r5rs) call-with-input-file call-with-output-file open-input-file open-output-file))
-
+          (only (scheme r5rs) call-with-input-file call-with-output-file open-input-file open-output-file with-input-from-file with-output-to-file))
   (export call-with-input-file call-with-output-file delete-file file-exists?
           open-binary-input-file open-binary-output-file open-input-file
-          open-output-file with-input-from-file with-output-to-file)
-
-  (begin (define (with-input-from-file path thunk)
-           (parameterize ((current-input-port (open-input-file path)))
-             (thunk)
-             (close-input-port (current-input-port))))
-
-         (define (with-output-to-file path thunk)
-           (parameterize ((current-output-port (open-output-file path)))
-             (thunk)
-             (close-output-port (current-output-port))))))
+          open-output-file with-input-from-file with-output-to-file))
 
 (define-library (scheme inexact)
   (import (only (meevax inexact) finite? infinite? nan?)

From 09dd8c71350f3f1ce2b09c797d212aef9dc32c33 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 9 Mar 2024 14:58:35 +0900
Subject: [PATCH 17/40] Fix `with-(input-from|output-to)-file` to return the
 value yielded by thunk

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md     |  6 +++---
 VERSION       |  2 +-
 basis/r4rs.ss | 10 ++++++----
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/README.md b/README.md
index 7487048e3..e9a7329f9 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.135_amd64.deb
+sudo apt install build/meevax_0.5.136_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.135.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.136.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.135_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.136_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index da9c7dd0e..3eac27980 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.135
+0.5.136
diff --git a/basis/r4rs.ss b/basis/r4rs.ss
index 499cbf63c..20714a17b 100644
--- a/basis/r4rs.ss
+++ b/basis/r4rs.ss
@@ -325,13 +325,15 @@
 
          (define (with-input-from-file path thunk)
            (parameterize ((current-input-port (open-input-file path)))
-             (thunk)
-             (close-input-port (current-input-port))))
+             (let ((result (thunk)))
+               (close-input-port (current-input-port))
+               result)))
 
          (define (with-output-to-file path thunk)
            (parameterize ((current-output-port (open-output-file path)))
-             (thunk)
-             (close-output-port (current-output-port))))
+             (let ((result (thunk)))
+               (close-output-port (current-output-port))
+               result)))
 
          (define close-input-port close)
 

From a592addb092efc8c6ee61a4a1f72801b7bb54234 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Thu, 14 Mar 2024 02:13:29 +0900
Subject: [PATCH 18/40] Add struct `simple_allocator<T>::rebind<U>`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                  |  6 +++---
 VERSION                                    |  2 +-
 include/meevax/kernel/pair.hpp             | 17 ++++++++++++-----
 include/meevax/memory/collector.hpp        |  7 +++++--
 include/meevax/memory/integer_set.hpp      | 17 ++++++++++++-----
 include/meevax/memory/simple_allocator.hpp |  6 ++++++
 6 files changed, 39 insertions(+), 16 deletions(-)

diff --git a/README.md b/README.md
index e9a7329f9..af275cf78 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.136_amd64.deb
+sudo apt install build/meevax_0.5.137_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.136.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.137.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.136_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.137_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 3eac27980..b05e146ae 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.136
+0.5.137
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 34344d818..971f85407 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -33,14 +33,22 @@ inline namespace kernel
 
   let extern unit;
 
-  template <typename T,
-            typename Allocator = collector::default_allocator<void>,
-            typename... Ts>
+  template <typename T, typename Allocator, typename... Ts>
   auto make(Ts&&... xs) -> decltype(auto)
   {
     return object::make<T, Allocator>(std::forward<decltype(xs)>(xs)...);
   }
 
+  template <typename T, typename... Ts>
+  auto make(Ts&&... xs) -> decltype(auto)
+  {
+    if constexpr (std::is_same_v<T, pair>) {
+      return object::make<T, simple_allocator<void>>(std::forward<decltype(xs)>(xs)...);
+    } else {
+      return object::make<T, collector::default_allocator<void>>(std::forward<decltype(xs)>(xs)...);
+    }
+  }
+
   template <typename T,
             typename Allocator = collector::default_allocator<void>>
   auto make(T&& x) -> decltype(auto)
@@ -180,8 +188,7 @@ inline namespace kernel
   template <typename T, typename U, REQUIRES(std::is_constructible<pair, T, U>)>
   auto operator |(T&& x, U&& y) -> decltype(auto)
   {
-    return make<pair, simple_allocator<void>>(std::forward<decltype(x)>(x),
-                                              std::forward<decltype(y)>(y));
+    return make<pair>(std::forward<decltype(x)>(x), std::forward<decltype(y)>(y));
   }
 
   inline auto cons = [](auto&&... xs) constexpr
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 725f251c0..454c09dbc 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -184,9 +184,12 @@ inline namespace memory
   private:
     static inline tag * cache = nullptr;
 
-    static inline integer_set<tag *, 16, 16, 16> tags {};
+    /*
+       0x0000'0000'0000'0000 ~ 0x7FFF'FFFF'FFFF'FFFF
+    */
+    static inline integer_set<tag *, 15, 16, 16> tags {};
 
-    static inline integer_set<mutator *, 16, 16, 16> mutators {};
+    static inline integer_set<mutator *, 15, 16, 16> mutators {};
 
     static inline std::size_t allocation = 0;
 
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index 606690d3f..89e3b4571 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -77,12 +77,19 @@ inline namespace memory
       {
         assert(data);
 
-        for (; good(); ++i, j = 0)
+        if (good())
         {
           if (data[i] and (iter = data[i]->lower_bound(j)).good())
           {
             return;
           }
+          else for (++i; good(); ++i)
+          {
+            if (data[i] and (iter = data[i]->lower_bound(0)).good())
+            {
+              return;
+            }
+          }
         }
 
         iter = {};
@@ -197,14 +204,14 @@ inline namespace memory
 
     auto insert(T value)
     {
-      if (auto [key, datum] = split(value); data[key])
+      if (auto [i, j] = split(value); data[i])
       {
-        data[key]->insert(datum);
+        data[i]->insert(j);
       }
       else
       {
-        data[key] = new subset();
-        data[key]->insert(datum);
+        data[i] = new subset();
+        data[i]->insert(j);
       }
     }
 
diff --git a/include/meevax/memory/simple_allocator.hpp b/include/meevax/memory/simple_allocator.hpp
index dbc08acfc..6dadbdddb 100644
--- a/include/meevax/memory/simple_allocator.hpp
+++ b/include/meevax/memory/simple_allocator.hpp
@@ -77,6 +77,12 @@ class simple_allocator
 
   using is_always_equal = std::false_type;
 
+  template <typename U>
+  struct rebind
+  {
+    using other = simple_allocator<U, Capacity>;
+  };
+
   explicit simple_allocator()
     : free_space { new block() }
   {}

From aab49476f8572459f605085240a69b026869764e Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Thu, 14 Mar 2024 05:53:10 +0900
Subject: [PATCH 19/40] Cleanup function `merge_constants`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |   6 +-
 VERSION                                       |   2 +-
 include/meevax/kernel/dynamic_environment.hpp |  23 ++--
 include/meevax/kernel/instruction.hpp         |  38 -------
 include/meevax/kernel/optimizer.hpp           | 104 +++++++++---------
 5 files changed, 70 insertions(+), 103 deletions(-)

diff --git a/README.md b/README.md
index af275cf78..e941be28f 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.137_amd64.deb
+sudo apt install build/meevax_0.5.138_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.137.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.138.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.137_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.138_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index b05e146ae..3eda6237a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.137
+0.5.138
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index df594807e..fc910a20f 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -238,15 +238,18 @@ inline namespace kernel
           *
           * ----------------------------------------------------------------- */
           d = cons(cdddr(c), d);
-          [[fallthrough]];
+          c = car(s) != f ? cadr(c) : caddr(c);
+          s = cdr(s);
+          goto fetch;
 
         case instruction::tail_select: /* --------------------------------------
           *
-          *  (<boolean> . s) e (%select c1 c2 . c) d => s e c' d
+          *  (<boolean> . s) e (%tail-select c1 c2) d => s e c' d
           *
           *  where c' = (if <boolean> c1 c2)
           *
           * ----------------------------------------------------------------- */
+          assert(cdddr(c).template is<null>());
           c = car(s) != f ? cadr(c) : caddr(c);
           s = cdr(s);
           goto fetch;
@@ -373,28 +376,29 @@ inline namespace kernel
           c = cdr(c);
           goto fetch;
 
-        case instruction::tail_letrec: /* --------------------------------------
+        case instruction::letrec: /* -------------------------------------------
           *
-          *  (<closure> xs . s) (<null> . e) (%letrec . c) d => () (set-car! e' xs) c' d
+          *  (<closure> xs . s) (<null> . e) (%letrec . c) d => () (set-car! e' xs) c' (s e c . d)
           *
           *  where <closure> = (c' . e')
           *
           * ----------------------------------------------------------------- */
           cadar(s) = cadr(s);
+          d = cons(cddr(s), cdr(e), cdr(c), d);
           c = caar(s);
           e = cdar(s);
           s = nullptr;
           goto fetch;
 
-        case instruction::letrec: /* -------------------------------------------
+        case instruction::tail_letrec: /* --------------------------------------
           *
-          *  (<closure> xs . s) (<null> . e) (%letrec . c) d => () (set-car! e' xs) c' (s e c . d)
+          *  (<closure> xs . s) (<null> . e) (%tail-letrec) d => () (set-car! e' xs) c' d
           *
           *  where <closure> = (c' . e')
           *
           * ----------------------------------------------------------------- */
+          assert(cdr(c).template is<null>());
           cadar(s) = cadr(s);
-          d = cons(cddr(s), cdr(e), cdr(c), d);
           c = caar(s);
           e = cdar(s);
           s = nullptr;
@@ -419,7 +423,8 @@ inline namespace kernel
           *  (x y . s) e (%cons . c) d => ((x . y) . s) e c d
           *
           * ----------------------------------------------------------------- */
-          s = cons(cons(car(s), cadr(s)), cddr(s));
+          car(s) = cons(car(s), cadr(s));
+          cdr(s) = cddr(s);
           c = cdr(c);
           goto fetch;
 
@@ -500,7 +505,7 @@ inline namespace kernel
 
         case instruction::install: /* ------------------------------------------
           *
-          *  (x . s) e (%intall i . c) d => (x . s) e c d
+          *  (x . s) e (%install i . c) d => (x . s) e c d
           *
           * ----------------------------------------------------------------- */
           assert(cadr(c).template is<exact_integer>());
diff --git a/include/meevax/kernel/instruction.hpp b/include/meevax/kernel/instruction.hpp
index 9cc90487c..2c6a4f7ab 100644
--- a/include/meevax/kernel/instruction.hpp
+++ b/include/meevax/kernel/instruction.hpp
@@ -52,44 +52,6 @@ inline namespace kernel
   };
 
   auto operator <<(std::ostream &, instruction const&) -> std::ostream &;
-
-  constexpr auto size(instruction const& datum)
-  {
-    switch (datum)
-    {
-      case instruction::call:
-      case instruction::cons:
-      case instruction::drop:
-      case instruction::dummy:
-      case instruction::join:
-      case instruction::letrec:
-      case instruction::return_:
-      case instruction::stop:
-      case instruction::tail_call:
-      case instruction::tail_letrec:
-        return 1;
-
-      case instruction::current:
-      case instruction::install:
-      case instruction::load_absolute:
-      case instruction::load_closure:
-      case instruction::load_constant:
-      case instruction::load_continuation:
-      case instruction::load_relative:
-      case instruction::load_variadic:
-      case instruction::store_absolute:
-      case instruction::store_relative:
-      case instruction::store_variadic:
-        return 2;
-
-      case instruction::select:
-      case instruction::tail_select:
-        return 3;
-
-      default:
-        return 0;
-    }
-  }
 } // namespace kernel
 } // namespace meevax
 
diff --git a/include/meevax/kernel/optimizer.hpp b/include/meevax/kernel/optimizer.hpp
index ec3877482..668fd747e 100644
--- a/include/meevax/kernel/optimizer.hpp
+++ b/include/meevax/kernel/optimizer.hpp
@@ -27,13 +27,13 @@ inline namespace kernel
   {
     static inline auto fmerge_constants = true;
 
-    static auto merge_constants(object const& c) -> object
+    static auto merge_constants(object & c) -> void
     {
-      if (not c.is<pair>() or not car(c).is<instruction>())
-      {
-        return c;
-      }
-      else switch (auto n = size(car(c).as<instruction>()); car(c).as<instruction>())
+      assert(c.is<pair>());
+
+      assert(car(c).is<instruction>());
+
+      switch (car(c).as<instruction>())
       {
       case instruction::load_constant: /* --------------------------------------
       *
@@ -49,69 +49,69 @@ inline namespace kernel
         if (tail(c, 2).is<pair>() and head(c, 2).is<instruction>() and head(c, 2).as<instruction>() == instruction::load_constant and
             tail(c, 4).is<pair>() and head(c, 4).is<instruction>() and head(c, 4).as<instruction>() == instruction::cons)
         {
-          return merge_constants(cons(head(c, 0),
-                                      cons(head(c, 3),
-                                           head(c, 1)),
-                                      merge_constants(tail(c, 5))));
-        }
-        else if (let const& c2 = merge_constants(tail(c, 2)); c2 == tail(c, 2))
-        {
-          return c;
+          cadr(c) = cons(head(c, 3),
+                         head(c, 1));
+          cddr(c) = tail(c, 5);
+          merge_constants(c);
         }
         else
         {
-          return cons(head(c, 0), head(c, 1), c2);
+          merge_constants(cddr(c));
         }
+        break;
 
-      default:
-        if (let const& cn = merge_constants(tail(c, n)); cn == tail(c, n))
-        {
-          return c;
-        }
-        else
-        {
-          return append(take(c, n), cn);
-        }
+      case instruction::join:
+      case instruction::tail_call:
+      case instruction::tail_letrec:
+      case instruction::return_:
+      case instruction::stop:
+        assert(cdr(c).is<null>());
+        break;
+
+      case instruction::call:
+      case instruction::cons:
+      case instruction::drop:
+      case instruction::dummy:
+      case instruction::letrec:
+        merge_constants(cdr(c));
+        break;
+
+      case instruction::current:
+      case instruction::install:
+      case instruction::load_absolute:
+      case instruction::load_relative:
+      case instruction::load_variadic:
+      case instruction::store_absolute:
+      case instruction::store_relative:
+      case instruction::store_variadic:
+        merge_constants(cddr(c));
+        break;
 
       case instruction::load_closure:
       case instruction::load_continuation:
-        if (let const& c1 = merge_constants(head(c, 1)),
-                       c2 = merge_constants(tail(c, 2));
-            c1 == head(c, 1) and
-            c2 == tail(c, 2))
-        {
-          return c;
-        }
-        else
-        {
-          return cons(head(c, 0), c1, c2);
-        }
+        merge_constants(cadr(c));
+        merge_constants(cddr(c));
+        break;
 
       case instruction::select:
+        merge_constants(cadr(c));
+        merge_constants(caddr(c));
+        merge_constants(cdddr(c));
+        break;
+
       case instruction::tail_select:
-        if (let const& c1 = merge_constants(head(c, 1)),
-                       c2 = merge_constants(head(c, 2)),
-                       c3 = merge_constants(tail(c, 3));
-            c1 == head(c, 1) and
-            c2 == head(c, 2) and
-            c3 == tail(c, 3))
-        {
-          return c;
-        }
-        else
-        {
-          return cons(head(c, 0), c1, c2, c3);
-        }
+        assert(cdddr(c).is<null>());
+        merge_constants(cadr(c));
+        merge_constants(caddr(c));
+        break;
       }
     }
 
-    static auto optimize(object const& c)
+    static auto optimize(let code)
     {
-      let code = c;
-
       if (fmerge_constants)
       {
-        code = merge_constants(code);
+        merge_constants(code);
       }
 
       return code;

From bc7427fa9c04d8c77f2ecbd8c2dd612ece3b15e0 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Thu, 14 Mar 2024 22:06:59 +0900
Subject: [PATCH 20/40] Move function `optimize` definition into new file
 `optimizer.cpp`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |   6 +-
 VERSION                                       |   2 +-
 include/meevax/kernel/environment.hpp         |   2 -
 include/meevax/kernel/instruction.hpp         |   3 +-
 include/meevax/kernel/optimizer.hpp           |  97 +--------------
 include/meevax/kernel/pair.hpp                |   1 +
 include/meevax/memory/collector.hpp           |   5 +-
 .../meevax/memory/heterogeneous_pointer.hpp   |   3 -
 include/meevax/memory/integer_set.hpp         |   3 +-
 src/kernel/environment.cpp                    |   1 +
 src/kernel/number.cpp                         |   1 +
 src/kernel/optimizer.cpp                      | 112 ++++++++++++++++++
 12 files changed, 125 insertions(+), 111 deletions(-)
 create mode 100644 src/kernel/optimizer.cpp

diff --git a/README.md b/README.md
index e941be28f..8df84297e 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.138_amd64.deb
+sudo apt install build/meevax_0.5.139_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.138.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.139.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.138_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.139_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 3eda6237a..c8fa5592c 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.138
+0.5.139
diff --git a/include/meevax/kernel/environment.hpp b/include/meevax/kernel/environment.hpp
index e3409cf08..5b945144f 100644
--- a/include/meevax/kernel/environment.hpp
+++ b/include/meevax/kernel/environment.hpp
@@ -19,7 +19,6 @@
 
 #include <meevax/kernel/configurator.hpp>
 #include <meevax/kernel/dynamic_environment.hpp>
-#include <meevax/kernel/optimizer.hpp>
 #include <meevax/kernel/syntactic_environment.hpp>
 
 namespace meevax
@@ -28,7 +27,6 @@ inline namespace kernel
 {
   struct environment : public configurator<environment>
                      , public dynamic_environment
-                     , public optimizer
                      , public syntactic_environment<environment>
   {
     using syntactic_environment::syntactic_environment;
diff --git a/include/meevax/kernel/instruction.hpp b/include/meevax/kernel/instruction.hpp
index 2c6a4f7ab..44526f689 100644
--- a/include/meevax/kernel/instruction.hpp
+++ b/include/meevax/kernel/instruction.hpp
@@ -17,14 +17,13 @@
 #ifndef INCLUDED_MEEVAX_KERNEL_INSTRUCTION_HPP
 #define INCLUDED_MEEVAX_KERNEL_INSTRUCTION_HPP
 
-#include <cstdint>
 #include <iostream>
 
 namespace meevax
 {
 inline namespace kernel
 {
-  enum class instruction : std::uint8_t
+  enum class instruction
   {
     call,              // a.k.a APP
     cons,              //
diff --git a/include/meevax/kernel/optimizer.hpp b/include/meevax/kernel/optimizer.hpp
index 668fd747e..0e4a8586a 100644
--- a/include/meevax/kernel/optimizer.hpp
+++ b/include/meevax/kernel/optimizer.hpp
@@ -17,106 +17,13 @@
 #ifndef INCLUDED_MEEVAX_KERNEL_OPTIMIZER_HPP
 #define INCLUDED_MEEVAX_KERNEL_OPTIMIZER_HPP
 
-#include <meevax/kernel/list.hpp>
+#include <meevax/kernel/pair.hpp>
 
 namespace meevax
 {
 inline namespace kernel
 {
-  struct optimizer
-  {
-    static inline auto fmerge_constants = true;
-
-    static auto merge_constants(object & c) -> void
-    {
-      assert(c.is<pair>());
-
-      assert(car(c).is<instruction>());
-
-      switch (car(c).as<instruction>())
-      {
-      case instruction::load_constant: /* --------------------------------------
-      *
-      *  (load-constant x
-      *   load-constant y
-      *   cons
-      *   ...)
-      *
-      *  => (load-constant (y . x)
-      *      ...)
-      *
-      * --------------------------------------------------------------------- */
-        if (tail(c, 2).is<pair>() and head(c, 2).is<instruction>() and head(c, 2).as<instruction>() == instruction::load_constant and
-            tail(c, 4).is<pair>() and head(c, 4).is<instruction>() and head(c, 4).as<instruction>() == instruction::cons)
-        {
-          cadr(c) = cons(head(c, 3),
-                         head(c, 1));
-          cddr(c) = tail(c, 5);
-          merge_constants(c);
-        }
-        else
-        {
-          merge_constants(cddr(c));
-        }
-        break;
-
-      case instruction::join:
-      case instruction::tail_call:
-      case instruction::tail_letrec:
-      case instruction::return_:
-      case instruction::stop:
-        assert(cdr(c).is<null>());
-        break;
-
-      case instruction::call:
-      case instruction::cons:
-      case instruction::drop:
-      case instruction::dummy:
-      case instruction::letrec:
-        merge_constants(cdr(c));
-        break;
-
-      case instruction::current:
-      case instruction::install:
-      case instruction::load_absolute:
-      case instruction::load_relative:
-      case instruction::load_variadic:
-      case instruction::store_absolute:
-      case instruction::store_relative:
-      case instruction::store_variadic:
-        merge_constants(cddr(c));
-        break;
-
-      case instruction::load_closure:
-      case instruction::load_continuation:
-        merge_constants(cadr(c));
-        merge_constants(cddr(c));
-        break;
-
-      case instruction::select:
-        merge_constants(cadr(c));
-        merge_constants(caddr(c));
-        merge_constants(cdddr(c));
-        break;
-
-      case instruction::tail_select:
-        assert(cdddr(c).is<null>());
-        merge_constants(cadr(c));
-        merge_constants(caddr(c));
-        break;
-      }
-    }
-
-    static auto optimize(let code)
-    {
-      if (fmerge_constants)
-      {
-        merge_constants(code);
-      }
-
-      return code;
-    }
-  };
+  auto optimize(object) -> object;
 } // namespace kernel
 } // namespace meevax
 
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 971f85407..1090926a4 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -261,6 +261,7 @@ inline namespace kernel
   inline constexpr auto cddddr = compose(cdr, cdddr);
 
   inline constexpr auto caddddr = compose(car, cddddr);
+  inline constexpr auto cdddddr = compose(cdr, cddddr);
 } // namespace kernel
 } // namespace meevax
 
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 454c09dbc..1599c2799 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -17,10 +17,9 @@
 #ifndef INCLUDED_MEEVAX_MEMORY_COLLECTOR_HPP
 #define INCLUDED_MEEVAX_MEMORY_COLLECTOR_HPP
 
-#include <cstddef>
-#include <memory>
+#include <cstddef> // std::size_t
+#include <memory> // std::allocator
 #include <unordered_map>
-#include <utility>
 
 #include <meevax/memory/integer_set.hpp>
 #include <meevax/memory/literal.hpp>
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
index da2fe35f9..efff46fd5 100644
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ b/include/meevax/memory/heterogeneous_pointer.hpp
@@ -17,15 +17,12 @@
 #ifndef INCLUDED_MEEVAX_MEMORY_HETEROGENEOUS_POINTER_HPP
 #define INCLUDED_MEEVAX_MEMORY_HETEROGENEOUS_POINTER_HPP
 
-#include <meevax/functional/combinator.hpp>
 #include <meevax/functional/compose.hpp>
 #include <meevax/iostream/escape_sequence.hpp>
 #include <meevax/iostream/lexical_cast.hpp>
 #include <meevax/type_traits/is_equality_comparable.hpp>
 #include <meevax/type_traits/is_output_streamable.hpp>
 #include <meevax/type_traits/requires.hpp>
-#include <meevax/utility/combination.hpp>
-#include <meevax/utility/debug.hpp>
 #include <meevax/utility/demangle.hpp>
 
 namespace meevax
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index 89e3b4571..ab5b6bb7c 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -17,9 +17,8 @@
 #ifndef INCLUDED_MEEVAX_MEMORY_INTEGER_SET_HPP
 #define INCLUDED_MEEVAX_MEMORY_INTEGER_SET_HPP
 
-#include <array>
 #include <cassert>
-#include <climits>
+#include <climits> // CHAR_BIT
 #include <cstdint>
 #include <iterator>
 #include <limits>
diff --git a/src/kernel/environment.cpp b/src/kernel/environment.cpp
index 6f45a99a2..e07b232de 100644
--- a/src/kernel/environment.cpp
+++ b/src/kernel/environment.cpp
@@ -17,6 +17,7 @@
 #include <meevax/kernel/environment.hpp>
 #include <meevax/kernel/input_file_port.hpp>
 #include <meevax/kernel/library.hpp>
+#include <meevax/kernel/optimizer.hpp>
 
 namespace meevax
 {
diff --git a/src/kernel/number.cpp b/src/kernel/number.cpp
index c723d3e93..9f2697d6a 100644
--- a/src/kernel/number.cpp
+++ b/src/kernel/number.cpp
@@ -21,6 +21,7 @@
 #include <meevax/kernel/ghost.hpp>
 #include <meevax/kernel/number.hpp>
 #include <meevax/kernel/string.hpp>
+#include <meevax/utility/combination.hpp>
 
 namespace meevax
 {
diff --git a/src/kernel/optimizer.cpp b/src/kernel/optimizer.cpp
new file mode 100644
index 000000000..8329dd2b0
--- /dev/null
+++ b/src/kernel/optimizer.cpp
@@ -0,0 +1,112 @@
+/*
+   Copyright 2018-2023 Tatsuya Yamasaki.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+#include <meevax/kernel/list.hpp>
+#include <meevax/kernel/optimizer.hpp>
+
+namespace meevax
+{
+inline namespace kernel
+{
+  auto merge_constants(object & c) -> void
+  {
+    assert(c.is<pair>());
+
+    assert(car(c).is<instruction>());
+
+    switch (car(c).as<instruction>())
+    {
+    case instruction::load_constant: /* ----------------------------------------
+    *
+    *  (load-constant x
+    *   load-constant y
+    *   cons
+    *   ...)
+    *
+    *  => (load-constant (y . x)
+    *      ...)
+    *
+    * ----------------------------------------------------------------------- */
+      if (cddr(c).is<pair>() and
+          caddr(c).is<instruction>() and caddr(c).as<instruction>() == instruction::load_constant and
+          cddddr(c).is<pair>() and
+          caddddr(c).is<instruction>() and caddddr(c).as<instruction>() == instruction::cons)
+      {
+        cadr(c) = cons(cadddr(c), cadr(c));
+        cddr(c) = cdddddr(c);
+        merge_constants(c);
+      }
+      else
+      {
+        merge_constants(cddr(c));
+      }
+      break;
+
+    case instruction::join:
+    case instruction::tail_call:
+    case instruction::tail_letrec:
+    case instruction::return_:
+    case instruction::stop:
+      assert(cdr(c).is<null>());
+      break;
+
+    case instruction::call:
+    case instruction::cons:
+    case instruction::drop:
+    case instruction::dummy:
+    case instruction::letrec:
+      merge_constants(cdr(c));
+      break;
+
+    case instruction::current:
+    case instruction::install:
+    case instruction::load_absolute:
+    case instruction::load_relative:
+    case instruction::load_variadic:
+    case instruction::store_absolute:
+    case instruction::store_relative:
+    case instruction::store_variadic:
+      merge_constants(cddr(c));
+      break;
+
+    case instruction::load_closure:
+    case instruction::load_continuation:
+      merge_constants(cadr(c));
+      merge_constants(cddr(c));
+      break;
+
+    case instruction::select:
+      merge_constants(cadr(c));
+      merge_constants(caddr(c));
+      merge_constants(cdddr(c));
+      break;
+
+    case instruction::tail_select:
+      assert(cdddr(c).is<null>());
+      merge_constants(cadr(c));
+      merge_constants(caddr(c));
+      break;
+    }
+  }
+
+  auto optimize(object code) -> object
+  {
+    merge_constants(code);
+
+    return code;
+  }
+} // namespace kernel
+} // namespace meevax

From 0a5a68120104ca7f40623d77a7954033c9574ff2 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 16 Mar 2024 12:06:10 +0900
Subject: [PATCH 21/40] Update `syntax::compile` from `std::function` to
 function pointer

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 +++---
 VERSION                                       |  2 +-
 .../meevax/kernel/syntactic_environment.hpp   | 19 ++++++++++---------
 .../meevax/memory/heterogeneous_pointer.hpp   |  4 +---
 4 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/README.md b/README.md
index 8df84297e..00a904cfb 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.139_amd64.deb
+sudo apt install build/meevax_0.5.140_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.139.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.140.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.139_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.140_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index c8fa5592c..3415d93c1 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.139
+0.5.140
diff --git a/include/meevax/kernel/syntactic_environment.hpp b/include/meevax/kernel/syntactic_environment.hpp
index e84330fdf..be6703de3 100644
--- a/include/meevax/kernel/syntactic_environment.hpp
+++ b/include/meevax/kernel/syntactic_environment.hpp
@@ -73,18 +73,17 @@ inline namespace kernel
 
     struct syntax
     {
-      using compiler = std::function<auto (syntactic_environment &,
-                                           object const& /* expression      */,
-                                           object const& /* bound_variables */,
-                                           object const& /* free_variables  */,
-                                           object const& /* continuation    */,
-                                           bool          /* tail            */) -> object>;
-
       std::string const name;
 
-      compiler const compile;
+      auto (*compile)(syntactic_environment &,
+                      object const& /* expression      */,
+                      object const& /* bound_variables */,
+                      object const& /* free_variables  */,
+                      object const& /* continuation    */,
+                      bool          /* tail            */) -> object;
 
-      explicit syntax(std::string const& name, compiler const& compile)
+      template <typename Compiler>
+      explicit syntax(std::string const& name, Compiler const& compile)
         : name { name }
         , compile { compile }
       {}
@@ -1076,6 +1075,8 @@ inline namespace kernel
         {
           return cdr(identity).as<syntax>().compile(*this, cdr(expression), bound_variables, free_variables, continuation, tail);
         }
+
+        assert(not cdr(identity).is_also<syntax>());
       }
 
       return syntax::call(*this, expression, bound_variables, free_variables, continuation, tail);
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
index efff46fd5..8583ac52a 100644
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ b/include/meevax/memory/heterogeneous_pointer.hpp
@@ -89,9 +89,7 @@ inline namespace memory
 
     using BasePointer<Top, Ts...>::get;
 
-    template <typename Bound,
-              typename Allocator = collector::default_allocator<void>,
-              typename... Us>
+    template <typename Bound, typename Allocator, typename... Us>
     static auto make(Us&&... xs)
     {
       if constexpr (std::is_same_v<Bound, Top>)

From 5d7c29ba7c0da4634f50324e548f86e064ae4b4e Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 17 Mar 2024 21:28:27 +0900
Subject: [PATCH 22/40] Remove template parameter `BasePointer` from
 `heterogeneous_pointer`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 ++---
 VERSION                                       |  2 +-
 include/meevax/memory/gc_pointer.hpp          |  7 +++---
 .../meevax/memory/heterogeneous_pointer.hpp   | 25 ++++++++++---------
 4 files changed, 20 insertions(+), 20 deletions(-)

diff --git a/README.md b/README.md
index 00a904cfb..3e55b5829 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.140_amd64.deb
+sudo apt install build/meevax_0.5.141_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.140.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.141.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.140_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.141_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 3415d93c1..e1f9e073c 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.140
+0.5.141
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index 3e179718e..d4f1926df 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -19,17 +19,16 @@
 
 #include <meevax/memory/collector.hpp>
 #include <meevax/memory/heterogeneous_pointer.hpp>
-#include <meevax/memory/nan_boxing_pointer.hpp>
 
 namespace meevax
 {
 inline namespace memory
 {
-  template <typename... Ts>
-  struct gc_pointer : public heterogeneous_pointer<nan_boxing_pointer, Ts...>
+  template <typename Top, typename... Ts>
+  struct gc_pointer : public heterogeneous_pointer<Top, Ts...>
                     , private collector::mutator
   {
-    using pointer = heterogeneous_pointer<nan_boxing_pointer, Ts...>;
+    using pointer = heterogeneous_pointer<Top, Ts...>;
 
     gc_pointer(gc_pointer const& gcp)
       : pointer { gcp }
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
index 8583ac52a..959f0770e 100644
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ b/include/meevax/memory/heterogeneous_pointer.hpp
@@ -20,6 +20,7 @@
 #include <meevax/functional/compose.hpp>
 #include <meevax/iostream/escape_sequence.hpp>
 #include <meevax/iostream/lexical_cast.hpp>
+#include <meevax/memory/nan_boxing_pointer.hpp>
 #include <meevax/type_traits/is_equality_comparable.hpp>
 #include <meevax/type_traits/is_output_streamable.hpp>
 #include <meevax/type_traits/requires.hpp>
@@ -31,8 +32,8 @@ inline namespace memory
 {
   using null = std::nullptr_t;
 
-  template <template <typename...> typename BasePointer, typename Top, typename... Ts>
-  class heterogeneous_pointer : public BasePointer<Top, Ts...>
+  template <typename Top, typename... Ts>
+  class heterogeneous_pointer : public nan_boxing_pointer<Top, Ts...>
   {
     template <typename Bound>
     struct binder : public virtual Top
@@ -83,11 +84,11 @@ inline namespace memory
     };
 
   public:
-    using BasePointer<Top, Ts...>::BasePointer;
+    using nan_boxing_pointer<Top, Ts...>::nan_boxing_pointer;
 
-    using BasePointer<Top, Ts...>::dereferenceable;
+    using nan_boxing_pointer<Top, Ts...>::dereferenceable;
 
-    using BasePointer<Top, Ts...>::get;
+    using nan_boxing_pointer<Top, Ts...>::get;
 
     template <typename Bound, typename Allocator, typename... Us>
     static auto make(Us&&... xs)
@@ -111,7 +112,7 @@ inline namespace memory
     {
       if constexpr (std::is_same_v<std::decay_t<U>, Top>)
       {
-        return BasePointer<Top, Ts...>::operator *();
+        return nan_boxing_pointer<Top, Ts...>::operator *();
       }
       else if constexpr (std::is_class_v<std::decay_t<U>>)
       {
@@ -126,7 +127,7 @@ inline namespace memory
       }
       else
       {
-        return BasePointer<Top, Ts...>::template as<U>();
+        return nan_boxing_pointer<Top, Ts...>::template as<U>();
       }
     }
 
@@ -135,7 +136,7 @@ inline namespace memory
     {
       if constexpr (std::is_same_v<std::decay_t<U>, Top>)
       {
-        return BasePointer<Top, Ts...>::operator *();
+        return nan_boxing_pointer<Top, Ts...>::operator *();
       }
       else if constexpr (std::is_class_v<std::decay_t<U>>)
       {
@@ -150,7 +151,7 @@ inline namespace memory
       }
       else
       {
-        return BasePointer<Top, Ts...>::template as<U>();
+        return nan_boxing_pointer<Top, Ts...>::template as<U>();
       }
     }
 
@@ -168,7 +169,7 @@ inline namespace memory
       }
       else
       {
-        return BasePointer<Top, Ts...>::compare(rhs);
+        return nan_boxing_pointer<Top, Ts...>::compare(rhs);
       }
     }
 
@@ -192,7 +193,7 @@ inline namespace memory
       }
       else
       {
-        return BasePointer<Top, Ts...>::type();
+        return nan_boxing_pointer<Top, Ts...>::type();
       }
     }
 
@@ -204,7 +205,7 @@ inline namespace memory
       }
       else
       {
-        return BasePointer<Top, Ts...>::write(os);
+        return nan_boxing_pointer<Top, Ts...>::write(os);
       }
     }
 

From 32edb8d4c8df10a57b1106e864c316fa80611709 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 17 Mar 2024 21:44:59 +0900
Subject: [PATCH 23/40] Cleanup struct template `heterogeneous_pointer`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 +--
 VERSION                                       |  2 +-
 .../meevax/memory/heterogeneous_pointer.hpp   | 50 +++++++++----------
 3 files changed, 28 insertions(+), 30 deletions(-)

diff --git a/README.md b/README.md
index 3e55b5829..ed4affe58 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.141_amd64.deb
+sudo apt install build/meevax_0.5.142_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.141.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.142.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.141_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.142_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index e1f9e073c..b913b4de1 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.141
+0.5.142
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
index 959f0770e..54e2c7e47 100644
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ b/include/meevax/memory/heterogeneous_pointer.hpp
@@ -84,11 +84,9 @@ inline namespace memory
     };
 
   public:
-    using nan_boxing_pointer<Top, Ts...>::nan_boxing_pointer;
+    using base_pointer = nan_boxing_pointer<Top, Ts...>;
 
-    using nan_boxing_pointer<Top, Ts...>::dereferenceable;
-
-    using nan_boxing_pointer<Top, Ts...>::get;
+    using base_pointer::base_pointer;
 
     template <typename Bound, typename Allocator, typename... Us>
     static auto make(Us&&... xs)
@@ -112,11 +110,11 @@ inline namespace memory
     {
       if constexpr (std::is_same_v<std::decay_t<U>, Top>)
       {
-        return nan_boxing_pointer<Top, Ts...>::operator *();
+        return base_pointer::operator *();
       }
       else if constexpr (std::is_class_v<std::decay_t<U>>)
       {
-        if (auto data = dynamic_cast<std::add_pointer_t<U>>(get()); data)
+        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
         {
           return *data;
         }
@@ -127,7 +125,7 @@ inline namespace memory
       }
       else
       {
-        return nan_boxing_pointer<Top, Ts...>::template as<U>();
+        return base_pointer::template as<U>();
       }
     }
 
@@ -136,11 +134,11 @@ inline namespace memory
     {
       if constexpr (std::is_same_v<std::decay_t<U>, Top>)
       {
-        return nan_boxing_pointer<Top, Ts...>::operator *();
+        return base_pointer::operator *();
       }
       else if constexpr (std::is_class_v<std::decay_t<U>>)
       {
-        if (auto data = dynamic_cast<std::add_pointer_t<U>>(get()); data)
+        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
         {
           return *data;
         }
@@ -151,7 +149,7 @@ inline namespace memory
       }
       else
       {
-        return nan_boxing_pointer<Top, Ts...>::template as<U>();
+        return base_pointer::template as<U>();
       }
     }
 
@@ -163,13 +161,13 @@ inline namespace memory
 
     inline auto compare(heterogeneous_pointer const& rhs) const -> bool
     {
-      if (dereferenceable())
+      if (base_pointer::dereferenceable())
       {
-        return *this ? get()->compare(rhs.get()) : rhs.is<null>();
+        return *this ? base_pointer::get()->compare(rhs.get()) : rhs.is<null>();
       }
       else
       {
-        return nan_boxing_pointer<Top, Ts...>::compare(rhs);
+        return base_pointer::compare(rhs);
       }
     }
 
@@ -182,30 +180,30 @@ inline namespace memory
     template <typename U, REQUIRES(std::is_class<U>)>
     inline auto is_also() const
     {
-      return dynamic_cast<std::add_pointer_t<U>>(get()) != nullptr;
+      return dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()) != nullptr;
     }
 
     inline auto type() const -> std::type_info const&
     {
-      if (dereferenceable())
+      if (base_pointer::dereferenceable())
       {
-        return *this ? get()->type() : typeid(null);
+        return *this ? base_pointer::get()->type() : typeid(null);
       }
       else
       {
-        return nan_boxing_pointer<Top, Ts...>::type();
+        return base_pointer::type();
       }
     }
 
     inline auto write(std::ostream & os) const -> std::ostream &
     {
-      if (dereferenceable())
+      if (base_pointer::dereferenceable())
       {
-        return *this ? get()->write(os) : os << magenta("()");
+        return *this ? base_pointer::get()->write(os) : os << magenta("()");
       }
       else
       {
-        return nan_boxing_pointer<Top, Ts...>::write(os);
+        return base_pointer::write(os);
       }
     }
 
@@ -216,32 +214,32 @@ inline namespace memory
 
     inline auto begin()
     {
-      return dereferenceable() and *this ? get()->begin() : typename Top::iterator();
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->begin() : typename Top::iterator();
     }
 
     inline auto begin() const
     {
-      return dereferenceable() and *this ? get()->cbegin() : typename Top::const_iterator();
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
     }
 
     inline auto cbegin() const
     {
-      return dereferenceable() and *this ? get()->cbegin() : typename Top::const_iterator();
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
     }
 
     inline auto end()
     {
-      return dereferenceable() and *this ? get()->end() : typename Top::iterator();
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->end() : typename Top::iterator();
     }
 
     inline auto end() const
     {
-      return dereferenceable() and *this ? get()->cend() : typename Top::const_iterator();
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
     }
 
     inline auto cend() const
     {
-      return dereferenceable() and *this ? get()->cend() : typename Top::const_iterator();
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
     }
   };
 } // namespace memory

From ab7991956e1574743a335445f3337c4ac34408b0 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 17 Mar 2024 22:40:29 +0900
Subject: [PATCH 24/40] Splice struct `heterogeneous_pointer` implementation
 into `gc_pointer`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                            |   6 +-
 VERSION                              |   2 +-
 include/meevax/kernel/pair.hpp       |   1 +
 include/meevax/memory/gc_pointer.hpp | 247 ++++++++++++++++++++++++---
 4 files changed, 233 insertions(+), 23 deletions(-)

diff --git a/README.md b/README.md
index ed4affe58..f8a494a2b 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.142_amd64.deb
+sudo apt install build/meevax_0.5.143_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.142.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.143.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.142_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.143_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index b913b4de1..46f0aee2d 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.142
+0.5.143
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 1090926a4..7e4c29cc5 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -17,6 +17,7 @@
 #ifndef INCLUDED_MEEVAX_KERNEL_PAIR_HPP
 #define INCLUDED_MEEVAX_KERNEL_PAIR_HPP
 
+#include <meevax/functional/compose.hpp>
 #include <meevax/kernel/character.hpp>
 #include <meevax/kernel/instruction.hpp>
 #include <meevax/memory/gc_pointer.hpp>
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index d4f1926df..fa78e01aa 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -17,37 +17,98 @@
 #ifndef INCLUDED_MEEVAX_MEMORY_GC_POINTER_HPP
 #define INCLUDED_MEEVAX_MEMORY_GC_POINTER_HPP
 
+#include <meevax/iostream/escape_sequence.hpp>
+#include <meevax/iostream/lexical_cast.hpp>
 #include <meevax/memory/collector.hpp>
-#include <meevax/memory/heterogeneous_pointer.hpp>
+#include <meevax/memory/nan_boxing_pointer.hpp>
+#include <meevax/type_traits/is_equality_comparable.hpp>
+#include <meevax/type_traits/is_output_streamable.hpp>
+#include <meevax/type_traits/requires.hpp>
+#include <meevax/utility/demangle.hpp>
 
 namespace meevax
 {
 inline namespace memory
 {
+  using null = std::nullptr_t;
+
   template <typename Top, typename... Ts>
-  struct gc_pointer : public heterogeneous_pointer<Top, Ts...>
+  struct gc_pointer : public nan_boxing_pointer<Top, Ts...>
                     , private collector::mutator
   {
-    using pointer = heterogeneous_pointer<Top, Ts...>;
+    template <typename Bound>
+    struct binder : public virtual Top
+                  , public Bound
+    {
+      template <typename... Us>
+      explicit constexpr binder(Us&&... xs)
+        : std::conditional_t<std::is_base_of_v<Top, Bound> and std::is_constructible_v<Top, Us...>, Top, Bound> {
+            std::forward<decltype(xs)>(xs)...
+          }
+      {}
+
+      auto compare([[maybe_unused]] Top const* top) const -> bool override
+      {
+        if constexpr (is_equality_comparable_v<Bound const&>)
+        {
+          if (auto const* bound = dynamic_cast<Bound const*>(top); bound)
+          {
+            return *bound == static_cast<Bound const&>(*this);
+          }
+          else
+          {
+            return std::is_same_v<Bound, null>;
+          }
+        }
+        else
+        {
+          return false;
+        }
+      }
+
+      auto type() const noexcept -> std::type_info const& override
+      {
+        return typeid(Bound);
+      }
+
+      auto write(std::ostream & os) const -> std::ostream & override
+      {
+        if constexpr (is_output_streamable_v<Bound const&>)
+        {
+          return os << static_cast<Bound const&>(*this);
+        }
+        else
+        {
+          return os << magenta("#,(") << green(typeid(Bound).name()) << faint(" #;", static_cast<Bound const*>(this)) << magenta(")");
+        }
+      }
+    };
+
+    using base_pointer = nan_boxing_pointer<Top, Ts...>;
 
     gc_pointer(gc_pointer const& gcp)
-      : pointer { gcp }
+      : base_pointer { gcp }
       , collector::mutator { gcp.object }
     {}
 
-    gc_pointer(pointer const& p)
-      : pointer { p }
-      , collector::mutator { locate(pointer::get()) }
+    gc_pointer(base_pointer const& p)
+      : base_pointer { p }
+      , collector::mutator { locate(base_pointer::get()) }
     {}
 
     gc_pointer(std::nullptr_t = nullptr)
     {}
 
-    template <typename T, REQUIRES(std::is_scalar<T>)>
+    explicit gc_pointer(Top * top) // TODO Top const*
+      : base_pointer { top }
+      , collector::mutator { locate(base_pointer::get()) }
+    {}
+
+    template <typename T, typename = std::enable_if_t<(std::is_same_v<T, Ts> or ... or std::is_same_v<T, double>)>>
     explicit gc_pointer(T const& datum)
-      : pointer { datum }
+      : base_pointer { datum }
     {
-      assert(pointer::get() == nullptr);
+      assert(base_pointer::get() == nullptr);
     }
 
     auto operator =(gc_pointer const& gcp) -> auto &
@@ -56,7 +117,7 @@ inline namespace memory
       return *this;
     }
 
-    auto operator =(pointer const& p) -> auto &
+    auto operator =(base_pointer const& p) -> auto &
     {
       reset(p);
       return *this;
@@ -70,26 +131,174 @@ inline namespace memory
 
     auto reset(gc_pointer const& gcp) -> void
     {
-      pointer::reset(gcp);
+      base_pointer::reset(gcp);
       collector::mutator::reset(gcp.object);
     }
 
-    auto reset(pointer const& p) -> void
+    auto reset(base_pointer const& p) -> void
     {
-      pointer::reset(p);
-      collector::mutator::reset(locate(pointer::get()));
+      base_pointer::reset(p);
+      collector::mutator::reset(locate(base_pointer::get()));
     }
 
     auto reset(std::nullptr_t = nullptr) -> void
     {
-      pointer::reset();
+      base_pointer::reset();
       collector::mutator::reset();
     }
 
-    template <typename T, typename Allocator, typename... Us>
-    static auto make(Us&&... xs) -> gc_pointer
+    template <typename Bound, typename Allocator, typename... Us>
+    static auto make(Us&&... xs)
+    {
+      if constexpr (std::is_same_v<Bound, Top>)
+      {
+        return gc_pointer(collector::make<Top, Allocator>(std::forward<decltype(xs)>(xs)...));
+      }
+      else if constexpr (std::is_class_v<Bound>)
+      {
+        return gc_pointer(collector::make<binder<Bound>, Allocator>(std::forward<decltype(xs)>(xs)...));
+      }
+      else
+      {
+        return gc_pointer(std::forward<decltype(xs)>(xs)...);
+      }
+    }
+
+    template <typename U>
+    inline auto as() const -> decltype(auto)
+    {
+      if constexpr (std::is_same_v<std::decay_t<U>, Top>)
+      {
+        return base_pointer::operator *();
+      }
+      else if constexpr (std::is_class_v<std::decay_t<U>>)
+      {
+        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
+        {
+          return *data;
+        }
+        else
+        {
+          throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
+        }
+      }
+      else
+      {
+        return base_pointer::template as<U>();
+      }
+    }
+
+    template <typename U>
+    inline auto as() -> decltype(auto)
+    {
+      if constexpr (std::is_same_v<std::decay_t<U>, Top>)
+      {
+        return base_pointer::operator *();
+      }
+      else if constexpr (std::is_class_v<std::decay_t<U>>)
+      {
+        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
+        {
+          return *data;
+        }
+        else
+        {
+          throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
+        }
+      }
+      else
+      {
+        return base_pointer::template as<U>();
+      }
+    }
+
+    template <typename U>
+    inline auto as_const() const -> decltype(auto)
+    {
+      return as<std::add_const_t<U>>();
+    }
+
+    inline auto compare(gc_pointer const& rhs) const -> bool
+    {
+      if (base_pointer::dereferenceable())
+      {
+        return *this ? base_pointer::get()->compare(rhs.get()) : rhs.is<null>();
+      }
+      else
+      {
+        return base_pointer::compare(rhs);
+      }
+    }
+
+    template <typename U>
+    inline auto is() const
+    {
+      return type() == typeid(std::decay_t<U>);
+    }
+
+    template <typename U, REQUIRES(std::is_class<U>)>
+    inline auto is_also() const
+    {
+      return dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()) != nullptr;
+    }
+
+    inline auto type() const -> std::type_info const&
+    {
+      if (base_pointer::dereferenceable())
+      {
+        return *this ? base_pointer::get()->type() : typeid(null);
+      }
+      else
+      {
+        return base_pointer::type();
+      }
+    }
+
+    inline auto write(std::ostream & os) const -> std::ostream &
+    {
+      if (base_pointer::dereferenceable())
+      {
+        return *this ? base_pointer::get()->write(os) : os << magenta("()");
+      }
+      else
+      {
+        return base_pointer::write(os);
+      }
+    }
+
+    friend auto operator <<(std::ostream & os, gc_pointer const& datum) -> std::ostream &
+    {
+      return datum.write(os);
+    }
+
+    inline auto begin()
+    {
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->begin() : typename Top::iterator();
+    }
+
+    inline auto begin() const
+    {
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
+    }
+
+    inline auto cbegin() const
+    {
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
+    }
+
+    inline auto end()
+    {
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->end() : typename Top::iterator();
+    }
+
+    inline auto end() const
+    {
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
+    }
+
+    inline auto cend() const
     {
-      return pointer::template make<T, Allocator>(std::forward<decltype(xs)>(xs)...);
+      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
     }
   };
 } // namespace memory

From 59547d3b10122d9f3f158f97ae18bfa7d76ba397 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 17 Mar 2024 22:57:00 +0900
Subject: [PATCH 25/40] Remove header `memory/heterogeneous_pointer.hpp`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |   6 +-
 VERSION                                       |   2 +-
 include/meevax/memory/gc_pointer.hpp          |  12 +-
 .../meevax/memory/heterogeneous_pointer.hpp   | 248 ------------------
 4 files changed, 10 insertions(+), 258 deletions(-)
 delete mode 100644 include/meevax/memory/heterogeneous_pointer.hpp

diff --git a/README.md b/README.md
index f8a494a2b..2693073a0 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.143_amd64.deb
+sudo apt install build/meevax_0.5.144_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.143.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.144.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.143_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.144_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 46f0aee2d..48655c806 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.143
+0.5.144
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index fa78e01aa..f4c7ad351 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -273,32 +273,32 @@ inline namespace memory
 
     inline auto begin()
     {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->begin() : typename Top::iterator();
+      return *this ? base_pointer::get()->begin() : typename Top::iterator();
     }
 
     inline auto begin() const
     {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
+      return *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
     }
 
     inline auto cbegin() const
     {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
+      return *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
     }
 
     inline auto end()
     {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->end() : typename Top::iterator();
+      return *this ? base_pointer::get()->end() : typename Top::iterator();
     }
 
     inline auto end() const
     {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
+      return *this ? base_pointer::get()->cend() : typename Top::const_iterator();
     }
 
     inline auto cend() const
     {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
+      return *this ? base_pointer::get()->cend() : typename Top::const_iterator();
     }
   };
 } // namespace memory
diff --git a/include/meevax/memory/heterogeneous_pointer.hpp b/include/meevax/memory/heterogeneous_pointer.hpp
deleted file mode 100644
index 54e2c7e47..000000000
--- a/include/meevax/memory/heterogeneous_pointer.hpp
+++ /dev/null
@@ -1,248 +0,0 @@
-/*
-   Copyright 2018-2023 Tatsuya Yamasaki.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-#ifndef INCLUDED_MEEVAX_MEMORY_HETEROGENEOUS_POINTER_HPP
-#define INCLUDED_MEEVAX_MEMORY_HETEROGENEOUS_POINTER_HPP
-
-#include <meevax/functional/compose.hpp>
-#include <meevax/iostream/escape_sequence.hpp>
-#include <meevax/iostream/lexical_cast.hpp>
-#include <meevax/memory/nan_boxing_pointer.hpp>
-#include <meevax/type_traits/is_equality_comparable.hpp>
-#include <meevax/type_traits/is_output_streamable.hpp>
-#include <meevax/type_traits/requires.hpp>
-#include <meevax/utility/demangle.hpp>
-
-namespace meevax
-{
-inline namespace memory
-{
-  using null = std::nullptr_t;
-
-  template <typename Top, typename... Ts>
-  class heterogeneous_pointer : public nan_boxing_pointer<Top, Ts...>
-  {
-    template <typename Bound>
-    struct binder : public virtual Top
-                  , public Bound
-    {
-      template <typename... Us>
-      explicit constexpr binder(Us&&... xs)
-        : std::conditional_t<std::is_base_of_v<Top, Bound> and std::is_constructible_v<Top, Us...>, Top, Bound> {
-            std::forward<decltype(xs)>(xs)...
-          }
-      {}
-
-      auto compare([[maybe_unused]] Top const* top) const -> bool override
-      {
-        if constexpr (is_equality_comparable_v<Bound const&>)
-        {
-          if (auto const* bound = dynamic_cast<Bound const*>(top); bound)
-          {
-            return *bound == static_cast<Bound const&>(*this);
-          }
-          else
-          {
-            return std::is_same_v<Bound, null>;
-          }
-        }
-        else
-        {
-          return false;
-        }
-      }
-
-      auto type() const noexcept -> std::type_info const& override
-      {
-        return typeid(Bound);
-      }
-
-      auto write(std::ostream & os) const -> std::ostream & override
-      {
-        if constexpr (is_output_streamable_v<Bound const&>)
-        {
-          return os << static_cast<Bound const&>(*this);
-        }
-        else
-        {
-          return os << magenta("#,(") << green(typeid(Bound).name()) << faint(" #;", static_cast<Bound const*>(this)) << magenta(")");
-        }
-      }
-    };
-
-  public:
-    using base_pointer = nan_boxing_pointer<Top, Ts...>;
-
-    using base_pointer::base_pointer;
-
-    template <typename Bound, typename Allocator, typename... Us>
-    static auto make(Us&&... xs)
-    {
-      if constexpr (std::is_same_v<Bound, Top>)
-      {
-        return heterogeneous_pointer(collector::make<Top, Allocator>(std::forward<decltype(xs)>(xs)...));
-      }
-      else if constexpr (std::is_class_v<Bound>)
-      {
-        return heterogeneous_pointer(collector::make<binder<Bound>, Allocator>(std::forward<decltype(xs)>(xs)...));
-      }
-      else
-      {
-        return heterogeneous_pointer(std::forward<decltype(xs)>(xs)...);
-      }
-    }
-
-    template <typename U>
-    inline auto as() const -> decltype(auto)
-    {
-      if constexpr (std::is_same_v<std::decay_t<U>, Top>)
-      {
-        return base_pointer::operator *();
-      }
-      else if constexpr (std::is_class_v<std::decay_t<U>>)
-      {
-        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
-        {
-          return *data;
-        }
-        else
-        {
-          throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
-        }
-      }
-      else
-      {
-        return base_pointer::template as<U>();
-      }
-    }
-
-    template <typename U>
-    inline auto as() -> decltype(auto)
-    {
-      if constexpr (std::is_same_v<std::decay_t<U>, Top>)
-      {
-        return base_pointer::operator *();
-      }
-      else if constexpr (std::is_class_v<std::decay_t<U>>)
-      {
-        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
-        {
-          return *data;
-        }
-        else
-        {
-          throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
-        }
-      }
-      else
-      {
-        return base_pointer::template as<U>();
-      }
-    }
-
-    template <typename U>
-    inline auto as_const() const -> decltype(auto)
-    {
-      return as<std::add_const_t<U>>();
-    }
-
-    inline auto compare(heterogeneous_pointer const& rhs) const -> bool
-    {
-      if (base_pointer::dereferenceable())
-      {
-        return *this ? base_pointer::get()->compare(rhs.get()) : rhs.is<null>();
-      }
-      else
-      {
-        return base_pointer::compare(rhs);
-      }
-    }
-
-    template <typename U>
-    inline auto is() const
-    {
-      return type() == typeid(std::decay_t<U>);
-    }
-
-    template <typename U, REQUIRES(std::is_class<U>)>
-    inline auto is_also() const
-    {
-      return dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()) != nullptr;
-    }
-
-    inline auto type() const -> std::type_info const&
-    {
-      if (base_pointer::dereferenceable())
-      {
-        return *this ? base_pointer::get()->type() : typeid(null);
-      }
-      else
-      {
-        return base_pointer::type();
-      }
-    }
-
-    inline auto write(std::ostream & os) const -> std::ostream &
-    {
-      if (base_pointer::dereferenceable())
-      {
-        return *this ? base_pointer::get()->write(os) : os << magenta("()");
-      }
-      else
-      {
-        return base_pointer::write(os);
-      }
-    }
-
-    friend auto operator <<(std::ostream & os, heterogeneous_pointer const& datum) -> std::ostream &
-    {
-      return datum.write(os);
-    }
-
-    inline auto begin()
-    {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->begin() : typename Top::iterator();
-    }
-
-    inline auto begin() const
-    {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
-    }
-
-    inline auto cbegin() const
-    {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
-    }
-
-    inline auto end()
-    {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->end() : typename Top::iterator();
-    }
-
-    inline auto end() const
-    {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
-    }
-
-    inline auto cend() const
-    {
-      return base_pointer::dereferenceable() and *this ? base_pointer::get()->cend() : typename Top::const_iterator();
-    }
-  };
-} // namespace memory
-} // namespace meevax
-
-#endif // INCLUDED_MEEVAX_MEMORY_HETEROGENEOUS_POINTER_HPP

From 6715eb5670c700505de35f3f2becaf958bfcfcaf Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Mon, 18 Mar 2024 01:16:07 +0900
Subject: [PATCH 26/40] Move struct template `binder` into `collector` from
 `gc_pointer`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                            |  6 +--
 VERSION                              |  2 +-
 include/meevax/kernel/pair.hpp       |  2 +
 include/meevax/memory/collector.hpp  | 51 ++++++++++++++++++++
 include/meevax/memory/gc_pointer.hpp | 69 ++++------------------------
 5 files changed, 65 insertions(+), 65 deletions(-)

diff --git a/README.md b/README.md
index 2693073a0..f3b6c9926 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.144_amd64.deb
+sudo apt install build/meevax_0.5.145_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.144.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.145.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.144_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.145_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 48655c806..31102a2c4 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.144
+0.5.145
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 7e4c29cc5..6268db123 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -26,6 +26,8 @@ namespace meevax
 {
 inline namespace kernel
 {
+  using null = std::nullptr_t;
+
   struct pair;
 
   using object = gc_pointer<pair, bool, int, float, character, instruction>;
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 1599c2799..3ee25598e 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -21,9 +21,12 @@
 #include <memory> // std::allocator
 #include <unordered_map>
 
+#include <meevax/iostream/escape_sequence.hpp>
 #include <meevax/memory/integer_set.hpp>
 #include <meevax/memory/literal.hpp>
 #include <meevax/memory/simple_allocator.hpp>
+#include <meevax/type_traits/is_equality_comparable.hpp>
+#include <meevax/type_traits/is_output_streamable.hpp>
 
 namespace meevax
 {
@@ -39,6 +42,54 @@ inline namespace memory
   class collector
   {
   public:
+    template <typename Top, typename Bound>
+    struct binder : public virtual Top
+                  , public Bound
+    {
+      template <typename... Us>
+      explicit constexpr binder(Us&&... xs)
+        : std::conditional_t<std::is_base_of_v<Top, Bound> and std::is_constructible_v<Top, Us...>, Top, Bound> {
+            std::forward<decltype(xs)>(xs)...
+          }
+      {}
+
+      auto compare([[maybe_unused]] Top const* top) const -> bool override
+      {
+        if constexpr (is_equality_comparable_v<Bound const&>)
+        {
+          if (auto const* bound = dynamic_cast<Bound const*>(top); bound)
+          {
+            return *bound == static_cast<Bound const&>(*this);
+          }
+          else
+          {
+            return std::is_same_v<Bound, std::nullptr_t>;
+          }
+        }
+        else
+        {
+          return false;
+        }
+      }
+
+      auto type() const noexcept -> std::type_info const& override
+      {
+        return typeid(Bound);
+      }
+
+      auto write(std::ostream & os) const -> std::ostream & override
+      {
+        if constexpr (is_output_streamable_v<Bound const&>)
+        {
+          return os << static_cast<Bound const&>(*this);
+        }
+        else
+        {
+          return os << magenta("#,(") << green(typeid(Bound).name()) << faint(" #;", static_cast<Bound const*>(this)) << magenta(")");
+        }
+      }
+    };
+
     struct tag
     {
       bool marked : 1;
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index f4c7ad351..af075c7c3 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -17,12 +17,9 @@
 #ifndef INCLUDED_MEEVAX_MEMORY_GC_POINTER_HPP
 #define INCLUDED_MEEVAX_MEMORY_GC_POINTER_HPP
 
-#include <meevax/iostream/escape_sequence.hpp>
 #include <meevax/iostream/lexical_cast.hpp>
 #include <meevax/memory/collector.hpp>
 #include <meevax/memory/nan_boxing_pointer.hpp>
-#include <meevax/type_traits/is_equality_comparable.hpp>
-#include <meevax/type_traits/is_output_streamable.hpp>
 #include <meevax/type_traits/requires.hpp>
 #include <meevax/utility/demangle.hpp>
 
@@ -30,60 +27,10 @@ namespace meevax
 {
 inline namespace memory
 {
-  using null = std::nullptr_t;
-
   template <typename Top, typename... Ts>
   struct gc_pointer : public nan_boxing_pointer<Top, Ts...>
                     , private collector::mutator
   {
-    template <typename Bound>
-    struct binder : public virtual Top
-                  , public Bound
-    {
-      template <typename... Us>
-      explicit constexpr binder(Us&&... xs)
-        : std::conditional_t<std::is_base_of_v<Top, Bound> and std::is_constructible_v<Top, Us...>, Top, Bound> {
-            std::forward<decltype(xs)>(xs)...
-          }
-      {}
-
-      auto compare([[maybe_unused]] Top const* top) const -> bool override
-      {
-        if constexpr (is_equality_comparable_v<Bound const&>)
-        {
-          if (auto const* bound = dynamic_cast<Bound const*>(top); bound)
-          {
-            return *bound == static_cast<Bound const&>(*this);
-          }
-          else
-          {
-            return std::is_same_v<Bound, null>;
-          }
-        }
-        else
-        {
-          return false;
-        }
-      }
-
-      auto type() const noexcept -> std::type_info const& override
-      {
-        return typeid(Bound);
-      }
-
-      auto write(std::ostream & os) const -> std::ostream & override
-      {
-        if constexpr (is_output_streamable_v<Bound const&>)
-        {
-          return os << static_cast<Bound const&>(*this);
-        }
-        else
-        {
-          return os << magenta("#,(") << green(typeid(Bound).name()) << faint(" #;", static_cast<Bound const*>(this)) << magenta(")");
-        }
-      }
-    };
-
     using base_pointer = nan_boxing_pointer<Top, Ts...>;
 
     gc_pointer(gc_pointer const& gcp)
@@ -99,13 +46,13 @@ inline namespace memory
     gc_pointer(std::nullptr_t = nullptr)
     {}
 
-    explicit gc_pointer(Top * top) // TODO Top const*
+    gc_pointer(Top * top) // TODO Top const*
       : base_pointer { top }
       , collector::mutator { locate(base_pointer::get()) }
     {}
 
     template <typename T, typename = std::enable_if_t<(std::is_same_v<T, Ts> or ... or std::is_same_v<T, double>)>>
-    explicit gc_pointer(T const& datum)
+    gc_pointer(T const& datum)
       : base_pointer { datum }
     {
       assert(base_pointer::get() == nullptr);
@@ -148,19 +95,19 @@ inline namespace memory
     }
 
     template <typename Bound, typename Allocator, typename... Us>
-    static auto make(Us&&... xs)
+    static auto make(Us&&... xs) -> gc_pointer
     {
       if constexpr (std::is_same_v<Bound, Top>)
       {
-        return gc_pointer(collector::make<Top, Allocator>(std::forward<decltype(xs)>(xs)...));
+        return collector::make<Top, Allocator>(std::forward<decltype(xs)>(xs)...);
       }
       else if constexpr (std::is_class_v<Bound>)
       {
-        return gc_pointer(collector::make<binder<Bound>, Allocator>(std::forward<decltype(xs)>(xs)...));
+        return collector::make<collector::binder<Top, Bound>, Allocator>(std::forward<decltype(xs)>(xs)...);
       }
       else
       {
-        return gc_pointer(std::forward<decltype(xs)>(xs)...);
+        return { std::forward<decltype(xs)>(xs)... };
       }
     }
 
@@ -222,7 +169,7 @@ inline namespace memory
     {
       if (base_pointer::dereferenceable())
       {
-        return *this ? base_pointer::get()->compare(rhs.get()) : rhs.is<null>();
+        return *this ? base_pointer::get()->compare(rhs.get()) : rhs.is<std::nullptr_t>();
       }
       else
       {
@@ -246,7 +193,7 @@ inline namespace memory
     {
       if (base_pointer::dereferenceable())
       {
-        return *this ? base_pointer::get()->type() : typeid(null);
+        return *this ? base_pointer::get()->type() : typeid(std::nullptr_t);
       }
       else
       {

From e03bcbd15bab3df4227bc6a27198a0633f4944d4 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Mon, 18 Mar 2024 21:45:45 +0900
Subject: [PATCH 27/40] Add new interface class `collector::top`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                           |  6 +++---
 VERSION                             |  2 +-
 include/meevax/kernel/pair.hpp      | 11 ++++++-----
 include/meevax/memory/collector.hpp | 15 +++++++++++++--
 src/kernel/pair.cpp                 |  6 ++++--
 5 files changed, 27 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index f3b6c9926..a4ca6d85a 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.145_amd64.deb
+sudo apt install build/meevax_0.5.146_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.145.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.146.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.145_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.146_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 31102a2c4..04384da07 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.145
+0.5.146
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 6268db123..6d4590988 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -68,7 +68,8 @@ inline namespace kernel
     return make<typename Traits<Ts...>::type, Allocator>(std::forward<decltype(xs)>(xs)...);
   }
 
-  struct pair : public std::pair<object, object>
+  struct pair : public collector::top
+              , public std::pair<object, object>
   {
     template <auto Const>
     struct forward_iterator
@@ -142,18 +143,18 @@ inline namespace kernel
 
     using const_iterator = forward_iterator<true>;
 
-    constexpr pair() = default;
+    pair() = default;
 
     template <typename T, typename U = std::nullptr_t, REQUIRES(std::is_constructible<std::pair<object, object>, T, U>)>
     explicit pair(T&& x, U&& y = nullptr)
       : std::pair<object, object> { std::forward<decltype(x)>(x), std::forward<decltype(y)>(y) }
     {}
 
-    virtual auto compare(pair const*) const -> bool;
+    auto compare(top const*) const -> bool override;
 
-    virtual auto type() const noexcept -> std::type_info const&;
+    auto type() const noexcept -> std::type_info const& override;
 
-    virtual auto write(std::ostream &) const -> std::ostream &;
+    auto write(std::ostream &) const -> std::ostream & override;
 
     constexpr auto begin() noexcept
     {
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 3ee25598e..f36aae789 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -42,6 +42,15 @@ inline namespace memory
   class collector
   {
   public:
+    struct top
+    {
+      virtual auto compare(top const*) const -> bool = 0;
+
+      virtual auto type() const noexcept -> std::type_info const& = 0;
+
+      virtual auto write(std::ostream &) const -> std::ostream & = 0;
+    };
+
     template <typename Top, typename Bound>
     struct binder : public virtual Top
                   , public Bound
@@ -53,11 +62,11 @@ inline namespace memory
           }
       {}
 
-      auto compare([[maybe_unused]] Top const* top) const -> bool override
+      auto compare([[maybe_unused]] top const* other) const -> bool override
       {
         if constexpr (is_equality_comparable_v<Bound const&>)
         {
-          if (auto const* bound = dynamic_cast<Bound const*>(top); bound)
+          if (auto const* bound = dynamic_cast<Bound const*>(other); bound)
           {
             return *bound == static_cast<Bound const&>(*this);
           }
@@ -263,6 +272,8 @@ inline namespace memory
     template <typename T, typename Allocator = default_allocator<void>, typename... Ts>
     static auto make(Ts&&... xs)
     {
+      static_assert(std::is_base_of_v<top, T>);
+
       if (allocation += sizeof(T); threshold < allocation)
       {
         collect();
diff --git a/src/kernel/pair.cpp b/src/kernel/pair.cpp
index b5993a2b1..912c91732 100644
--- a/src/kernel/pair.cpp
+++ b/src/kernel/pair.cpp
@@ -22,9 +22,11 @@ inline namespace kernel
 {
   let unit = nullptr;
 
-  auto pair::compare(pair const* that) const -> bool
+  auto pair::compare(top const* other) const -> bool
   {
-    return that and *this == *that;
+    auto pare = dynamic_cast<pair const*>(other);
+
+    return pare and *this == *pare;
   }
 
   auto pair::type() const noexcept -> std::type_info const&

From 658ea8ee1a7cd4429a2898f1069bb5d01ac5ff97 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Mon, 18 Mar 2024 23:50:23 +0900
Subject: [PATCH 28/40] Add new member function `integer_set<>::contains`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                             |  6 +++---
 VERSION                               |  2 +-
 include/meevax/memory/collector.hpp   | 13 ++++++++-----
 include/meevax/memory/integer_set.hpp | 13 +++++++++++++
 src/memory/collector.cpp              |  2 ++
 5 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/README.md b/README.md
index a4ca6d85a..036b70b02 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.146_amd64.deb
+sudo apt install build/meevax_0.5.147_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.146.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.147.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.146_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.147_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 04384da07..a99047e25 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.146
+0.5.147
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index f36aae789..be7b25450 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -240,15 +240,18 @@ inline namespace memory
     template <typename... Ts>
     using default_allocator = std::allocator<Ts...>;
 
-  private:
-    static inline tag * cache = nullptr;
-
     /*
        0x0000'0000'0000'0000 ~ 0x7FFF'FFFF'FFFF'FFFF
     */
-    static inline integer_set<tag *, 15, 16, 16> tags {};
+    template <typename T>
+    using pointer_set = integer_set<T *, 15, 16, 16>;
+
+  private:
+    static inline tag * cache = nullptr;
+
+    static inline pointer_set<tag> tags {};
 
-    static inline integer_set<mutator *, 15, 16, 16> mutators {};
+    static inline pointer_set<mutator> mutators {};
 
     static inline std::size_t allocation = 0;
 
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index ab5b6bb7c..b97f97351 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -220,6 +220,12 @@ inline namespace memory
       data[i]->erase(j);
     }
 
+    auto contains(T value) noexcept -> bool
+    {
+      auto [i, j] = split(value);
+      return data[i] and data[i]->contains(j);
+    }
+
     auto begin() const noexcept
     {
       return const_iterator(this, 0);
@@ -386,6 +392,13 @@ inline namespace memory
       data[i] &= ~(1ul << j);
     }
 
+    auto contains(T value) noexcept -> bool
+    {
+      auto i = reinterpret_cast<std::size_t>(value) / 64;
+      auto j = reinterpret_cast<std::size_t>(value) % 64;
+      return data[i] & (1ul << j);
+    }
+
     auto lower_bound(T value) const noexcept
     {
       return const_iterator(this, reinterpret_cast<std::size_t>(value));
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index 8b93fde75..6a75dfab0 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -146,6 +146,8 @@ inline namespace memory
   {
     assert(tag);
 
+    assert(tags.contains(tag));
+
     if (not tag->marked)
     {
       tag->marked = true;

From 98163b2fddea2a2dac32a794b4abaffc1194bb22 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Tue, 19 Mar 2024 01:21:03 +0900
Subject: [PATCH 29/40] Remove bitfield member `tag::marked`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                             |  6 ++--
 VERSION                               |  2 +-
 include/meevax/memory/collector.hpp   | 15 ++++----
 include/meevax/memory/integer_set.hpp |  5 +++
 src/memory/collector.cpp              | 49 ++++++++++++++-------------
 5 files changed, 41 insertions(+), 36 deletions(-)

diff --git a/README.md b/README.md
index 036b70b02..fc28a1f12 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.147_amd64.deb
+sudo apt install build/meevax_0.5.148_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.147.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.148.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.147_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.148_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index a99047e25..a1edab0a1 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.147
+0.5.148
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index be7b25450..f06ee34a0 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -101,18 +101,15 @@ inline namespace memory
 
     struct tag
     {
-      bool marked : 1;
-
-      std::size_t size : 15;
+      std::size_t size : 16;
 
       std::uintptr_t address : 48;
 
       explicit tag(void const* const address, std::size_t size)
-        : marked  { false }
-        , size    { size }
+        : size    { size }
         , address { reinterpret_cast<std::uintptr_t>(address) }
       {
-        assert(size < (1u << 15));
+        assert(size < (1u << 16));
       }
 
       virtual ~tag() = default;
@@ -306,11 +303,11 @@ inline namespace memory
 
     static auto dlsym(std::string const&, void * const) -> void *;
 
-    static auto mark() noexcept -> void;
+    static auto mark() noexcept -> pointer_set<tag>;
 
-    static auto mark(tag * const) noexcept -> void;
+    static auto mark(tag * const, pointer_set<tag> &) noexcept -> void;
 
-    static auto sweep() -> void;
+    static auto sweep(pointer_set<tag> &&) -> void;
   };
 
   static collector default_collector {};
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index b97f97351..fa8c8b52e 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -246,6 +246,11 @@ inline namespace memory
     {
       return std::distance(begin(), end());
     }
+
+    auto swap(integer_set & other)
+    {
+      std::swap(data, other.data);
+    }
   };
 
   template <typename T, std::size_t E>
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index 6a75dfab0..bcdd433fa 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -59,12 +59,12 @@ inline namespace memory
   {
     allocation = 0;
 
-    return mark(), sweep();
+    return sweep(mark());
   }
 
   auto collector::count() noexcept -> std::size_t
   {
-    return std::size(tags);
+    return tags.size();
   }
 
   auto collector::dlclose(void * const handle) -> void
@@ -112,7 +112,7 @@ inline namespace memory
     }
   }
 
-  auto collector::mark() noexcept -> void
+  auto collector::mark() noexcept -> pointer_set<tag>
   {
     auto is_root_object = [begin = tags.begin()](mutator * given)
     {
@@ -130,53 +130,56 @@ inline namespace memory
       return iter == begin or not (*--iter)->contains(given);
     };
 
+    auto marked_tags = pointer_set<tag>();
+
     for (auto&& mutator : mutators)
     {
       assert(mutator);
       assert(mutator->object);
 
-      if (not mutator->object->marked and is_root_object(mutator))
+      if (not marked_tags.contains(mutator->object) and is_root_object(mutator))
       {
-        mark(mutator->object);
+        mark(mutator->object, marked_tags);
       }
     }
+
+    return marked_tags;
   }
 
-  auto collector::mark(tag * const tag) noexcept -> void
+  auto collector::mark(tag * const object, pointer_set<tag> & marked_tags) noexcept -> void
   {
-    assert(tag);
+    assert(object);
 
-    assert(tags.contains(tag));
+    assert(tags.contains(object));
 
-    if (not tag->marked)
+    if (not marked_tags.contains(object))
     {
-      tag->marked = true;
+      marked_tags.insert(object);
 
-      const auto lower_address = reinterpret_cast<mutator *>(tag->lower_address());
-      const auto upper_address = reinterpret_cast<mutator *>(tag->upper_address());
+      const auto lower_address = reinterpret_cast<mutator *>(object->lower_address());
+      const auto upper_address = reinterpret_cast<mutator *>(object->upper_address());
 
       for (auto lower = mutators.lower_bound(lower_address),
                 upper = mutators.lower_bound(upper_address); lower != upper; ++lower)
       {
-        mark((*lower)->object);
+        mark((*lower)->object, marked_tags);
       }
     }
   }
 
-  auto collector::sweep() -> void
+  auto collector::sweep(pointer_set<tag> && marked_tags) -> void
   {
+    for (auto&& marked_tag : marked_tags)
+    {
+      tags.erase(marked_tag);
+    }
+
     for (auto&& tag : tags)
     {
-      if (tag->marked)
-      {
-        tag->marked = false;
-      }
-      else
-      {
-        delete tag;
-        tags.erase(tag);
-      }
+      delete tag;
     }
+
+    tags.swap(marked_tags);
   }
 } // namespace memory
 } // namespace meevax

From 71598d99fa9ede9c8ff5cfe0f6ad5913a677d606 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Wed, 20 Mar 2024 23:20:53 +0900
Subject: [PATCH 30/40] Update the pointer handled by `collector` to const

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                           |  6 +++---
 VERSION                             |  2 +-
 include/meevax/memory/collector.hpp | 24 ++++++++++++------------
 src/memory/collector.cpp            | 18 +++++++-----------
 4 files changed, 23 insertions(+), 27 deletions(-)

diff --git a/README.md b/README.md
index fc28a1f12..92bbc98fa 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.148_amd64.deb
+sudo apt install build/meevax_0.5.149_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.148.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.149.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.148_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.149_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index a1edab0a1..033d9dd31 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.148
+0.5.149
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index f06ee34a0..c8bf17122 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -114,19 +114,19 @@ inline namespace memory
 
       virtual ~tag() = default;
 
-      auto lower_address() const noexcept
+      auto begin() const
       {
-        return address;
+        return mutators.lower_bound(reinterpret_cast<mutator const*>(address));
       }
 
-      auto upper_address() const noexcept
+      auto end() const
       {
-        return address + size;
+        return mutators.lower_bound(reinterpret_cast<mutator const*>(address + size));
       }
 
       auto contains(void const* const data) const noexcept
       {
-        return reinterpret_cast<void const*>(lower_address()) <= data and data < reinterpret_cast<void const*>(upper_address());
+        return reinterpret_cast<void const*>(address) <= data and data < reinterpret_cast<void const*>(address + size);
       }
     };
 
@@ -180,11 +180,11 @@ inline namespace memory
       friend class collector;
 
     protected:
-      tag * object = nullptr;
+      tag const* object = nullptr;
 
       constexpr mutator() = default;
 
-      explicit mutator(tag * object) noexcept
+      explicit mutator(tag const* object) noexcept
         : object { object }
       {
         if (object)
@@ -201,7 +201,7 @@ inline namespace memory
         }
       }
 
-      auto reset(tag * after = nullptr) noexcept -> void
+      auto reset(tag const* after = nullptr) noexcept -> void
       {
         if (auto before = std::exchange(object, after); not before and after)
         {
@@ -213,7 +213,7 @@ inline namespace memory
         }
       }
 
-      static auto locate(void * const data) noexcept -> tag *
+      static auto locate(void const* const data) noexcept -> tag const*
       {
         if (not data)
         {
@@ -223,7 +223,7 @@ inline namespace memory
         {
           return cache;
         }
-        else if (auto iter = tags.lower_bound(reinterpret_cast<tag *>(data)); iter != tags.begin() and (*--iter)->contains(data))
+        else if (auto iter = tags.lower_bound(reinterpret_cast<tag const*>(data)); iter != tags.begin() and (*--iter)->contains(data))
         {
           return *iter;
         }
@@ -241,7 +241,7 @@ inline namespace memory
        0x0000'0000'0000'0000 ~ 0x7FFF'FFFF'FFFF'FFFF
     */
     template <typename T>
-    using pointer_set = integer_set<T *, 15, 16, 16>;
+    using pointer_set = integer_set<T const*, 15, 16, 16>;
 
   private:
     static inline tag * cache = nullptr;
@@ -305,7 +305,7 @@ inline namespace memory
 
     static auto mark() noexcept -> pointer_set<tag>;
 
-    static auto mark(tag * const, pointer_set<tag> &) noexcept -> void;
+    static auto mark(tag const* const, pointer_set<tag> &) noexcept -> void;
 
     static auto sweep(pointer_set<tag> &&) -> void;
   };
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index bcdd433fa..f6edd7460 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -114,7 +114,7 @@ inline namespace memory
 
   auto collector::mark() noexcept -> pointer_set<tag>
   {
-    auto is_root_object = [begin = tags.begin()](mutator * given)
+    auto is_root_object = [begin = tags.begin()](mutator const* given) // TODO INEFFICIENT!
     {
       /*
          If the given mutator is a non-root object, then an object containing
@@ -125,7 +125,7 @@ inline namespace memory
          base-address + object-size. The tag is present to keep track of the
          base-address and size of the object needed here.
       */
-      auto iter = tags.lower_bound(reinterpret_cast<tag *>(given));
+      auto iter = tags.lower_bound(reinterpret_cast<tag const*>(given));
 
       return iter == begin or not (*--iter)->contains(given);
     };
@@ -146,7 +146,7 @@ inline namespace memory
     return marked_tags;
   }
 
-  auto collector::mark(tag * const object, pointer_set<tag> & marked_tags) noexcept -> void
+  auto collector::mark(tag const* const object, pointer_set<tag> & marked_tags) noexcept -> void
   {
     assert(object);
 
@@ -156,25 +156,21 @@ inline namespace memory
     {
       marked_tags.insert(object);
 
-      const auto lower_address = reinterpret_cast<mutator *>(object->lower_address());
-      const auto upper_address = reinterpret_cast<mutator *>(object->upper_address());
-
-      for (auto lower = mutators.lower_bound(lower_address),
-                upper = mutators.lower_bound(upper_address); lower != upper; ++lower)
+      for (auto each : *object)
       {
-        mark((*lower)->object, marked_tags);
+        mark(each->object, marked_tags);
       }
     }
   }
 
   auto collector::sweep(pointer_set<tag> && marked_tags) -> void
   {
-    for (auto&& marked_tag : marked_tags)
+    for (auto marked_tag : marked_tags)
     {
       tags.erase(marked_tag);
     }
 
-    for (auto&& tag : tags)
+    for (auto tag : tags)
     {
       delete tag;
     }

From b385305129810e938b2f845c48b8ba9348f3fdb8 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Thu, 21 Mar 2024 01:06:19 +0900
Subject: [PATCH 31/40] Unify `tag` and `tagged` into `top` and `binder`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                            |   6 +-
 VERSION                              |   2 +-
 include/meevax/kernel/pair.hpp       |  26 ++++--
 include/meevax/memory/collector.hpp  | 126 +++++++++++----------------
 include/meevax/memory/gc_pointer.hpp |   8 +-
 src/memory/collector.cpp             |  51 ++++++-----
 6 files changed, 104 insertions(+), 115 deletions(-)

diff --git a/README.md b/README.md
index 92bbc98fa..e8f194644 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.149_amd64.deb
+sudo apt install build/meevax_0.5.150_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.149.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.150.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.149_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.150_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 033d9dd31..5a23fcf60 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.149
+0.5.150
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 6d4590988..322473b69 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -68,7 +68,7 @@ inline namespace kernel
     return make<typename Traits<Ts...>::type, Allocator>(std::forward<decltype(xs)>(xs)...);
   }
 
-  struct pair : public collector::top
+  struct pair : public virtual collector::top
               , public std::pair<object, object>
   {
     template <auto Const>
@@ -150,38 +150,50 @@ inline namespace kernel
       : std::pair<object, object> { std::forward<decltype(x)>(x), std::forward<decltype(y)>(y) }
     {}
 
+    ~pair() override = default;
+
     auto compare(top const*) const -> bool override;
 
     auto type() const noexcept -> std::type_info const& override;
 
     auto write(std::ostream &) const -> std::ostream & override;
 
-    constexpr auto begin() noexcept
+    auto lower() const noexcept -> std::uintptr_t override
+    {
+      return reinterpret_cast<std::uintptr_t>(this);
+    }
+
+    auto upper() const noexcept -> std::uintptr_t override
+    {
+      return reinterpret_cast<std::uintptr_t>(this) + sizeof(*this);
+    }
+
+    auto begin() noexcept
     {
       return iterator(this);
     }
 
-    constexpr auto begin() const noexcept
+    auto begin() const noexcept
     {
       return const_iterator(this);
     }
 
-    constexpr auto end() noexcept
+    auto end() noexcept
     {
       return iterator(nullptr);
     }
 
-    constexpr auto end() const noexcept
+    auto end() const noexcept
     {
       return const_iterator(nullptr);
     }
 
-    constexpr auto cbegin() const -> const_iterator
+    auto cbegin() const -> const_iterator
     {
       return std::as_const(*this).begin();
     }
 
-    constexpr auto cend() const noexcept
+    auto cend() const noexcept
     {
       return std::as_const(*this).end();
     }
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index c8bf17122..7302b9197 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -44,17 +44,48 @@ inline namespace memory
   public:
     struct top
     {
+      virtual ~top() = default;
+
       virtual auto compare(top const*) const -> bool = 0;
 
       virtual auto type() const noexcept -> std::type_info const& = 0;
 
       virtual auto write(std::ostream &) const -> std::ostream & = 0;
+
+      virtual auto lower() const noexcept -> std::uintptr_t = 0;
+
+      virtual auto upper() const noexcept -> std::uintptr_t = 0;
+
+      auto contains(void const* const data) const noexcept
+      {
+        return reinterpret_cast<void const*>(lower()) <= data and data < reinterpret_cast<void const*>(upper());
+      }
     };
 
-    template <typename Top, typename Bound>
-    struct binder : public virtual Top
+    static inline auto cleared = false;
+
+    template <typename Top, typename Bound, typename AllocatorTraits = std::allocator_traits<std::allocator<void>>>
+    struct binder : public virtual std::conditional_t<std::is_same_v<Top, Bound>, top, Top>
                   , public Bound
     {
+      struct allocator_type : public AllocatorTraits::template rebind_alloc<binder<Top, Bound, AllocatorTraits>>
+      {
+        ~allocator_type()
+        {
+          /*
+             Execute clear before any static allocator is destroyed. Otherwise,
+             when the destructor of the collector executes clear, the collector
+             may touch the freed memory of the stateful allocator.
+          */
+          if (not std::exchange(cleared, true))
+          {
+            clear();
+          }
+        }
+      };
+
+      static inline auto allocator = allocator_type();
+
       template <typename... Us>
       explicit constexpr binder(Us&&... xs)
         : std::conditional_t<std::is_base_of_v<Top, Bound> and std::is_constructible_v<Top, Us...>, Top, Bound> {
@@ -62,6 +93,8 @@ inline namespace memory
           }
       {}
 
+      ~binder() override = default;
+
       auto compare([[maybe_unused]] top const* other) const -> bool override
       {
         if constexpr (is_equality_comparable_v<Bound const&>)
@@ -97,71 +130,16 @@ inline namespace memory
           return os << magenta("#,(") << green(typeid(Bound).name()) << faint(" #;", static_cast<Bound const*>(this)) << magenta(")");
         }
       }
-    };
-
-    struct tag
-    {
-      std::size_t size : 16;
-
-      std::uintptr_t address : 48;
-
-      explicit tag(void const* const address, std::size_t size)
-        : size    { size }
-        , address { reinterpret_cast<std::uintptr_t>(address) }
-      {
-        assert(size < (1u << 16));
-      }
-
-      virtual ~tag() = default;
-
-      auto begin() const
-      {
-        return mutators.lower_bound(reinterpret_cast<mutator const*>(address));
-      }
 
-      auto end() const
+      auto lower() const noexcept -> std::uintptr_t override
       {
-        return mutators.lower_bound(reinterpret_cast<mutator const*>(address + size));
+        return reinterpret_cast<std::uintptr_t>(this);
       }
 
-      auto contains(void const* const data) const noexcept
+      auto upper() const noexcept -> std::uintptr_t override
       {
-        return reinterpret_cast<void const*>(address) <= data and data < reinterpret_cast<void const*>(address + size);
+        return reinterpret_cast<std::uintptr_t>(this) + sizeof(*this);
       }
-    };
-
-    static inline auto cleared = false;
-
-    template <typename T, typename AllocatorTraits>
-    struct tagged : public tag
-    {
-      struct allocator_type : public AllocatorTraits::template rebind_alloc<tagged<T, AllocatorTraits>>
-      {
-        ~allocator_type()
-        {
-          /*
-             Execute clear before any static allocator is destroyed. Otherwise,
-             when the destructor of the collector executes clear, the collector
-             may touch the freed memory of the stateful allocator.
-          */
-          if (not std::exchange(cleared, true))
-          {
-            clear();
-          }
-        }
-      };
-
-      static inline auto allocator = allocator_type();
-
-      T value;
-
-      template <typename... Ts>
-      explicit tagged(Ts&&... xs)
-        : tag   { std::addressof(value), sizeof(T) }
-        , value { std::forward<decltype(xs)>(xs)... }
-      {}
-
-      ~tagged() override = default;
 
       auto operator new(std::size_t) -> void *
       {
@@ -180,11 +158,11 @@ inline namespace memory
       friend class collector;
 
     protected:
-      tag const* object = nullptr;
+      top const* object = nullptr;
 
       constexpr mutator() = default;
 
-      explicit mutator(tag const* object) noexcept
+      explicit mutator(top const* object) noexcept
         : object { object }
       {
         if (object)
@@ -201,7 +179,7 @@ inline namespace memory
         }
       }
 
-      auto reset(tag const* after = nullptr) noexcept -> void
+      auto reset(top const* after = nullptr) noexcept -> void
       {
         if (auto before = std::exchange(object, after); not before and after)
         {
@@ -213,7 +191,7 @@ inline namespace memory
         }
       }
 
-      static auto locate(void const* const data) noexcept -> tag const*
+      static auto locate(void const* const data) noexcept -> top const*
       {
         if (not data)
         {
@@ -223,7 +201,7 @@ inline namespace memory
         {
           return cache;
         }
-        else if (auto iter = tags.lower_bound(reinterpret_cast<tag const*>(data)); iter != tags.begin() and (*--iter)->contains(data))
+        else if (auto iter = objects.lower_bound(reinterpret_cast<top const*>(data)); iter != objects.begin() and (*--iter)->contains(data))
         {
           return *iter;
         }
@@ -244,9 +222,9 @@ inline namespace memory
     using pointer_set = integer_set<T const*, 15, 16, 16>;
 
   private:
-    static inline tag * cache = nullptr;
+    static inline top * cache = nullptr;
 
-    static inline pointer_set<tag> tags {};
+    static inline pointer_set<top> objects {};
 
     static inline pointer_set<mutator> mutators {};
 
@@ -279,11 +257,11 @@ inline namespace memory
         collect();
       }
 
-      if (auto data = new tagged<T, std::allocator_traits<Allocator>>(std::forward<decltype(xs)>(xs)...); data)
+      if (auto data = new T(std::forward<decltype(xs)>(xs)...); data)
       {
-        tags.insert(cache = data);
+        objects.insert(cache = data);
 
-        return std::addressof(data->value);
+        return data;
       }
       else
       {
@@ -303,11 +281,11 @@ inline namespace memory
 
     static auto dlsym(std::string const&, void * const) -> void *;
 
-    static auto mark() noexcept -> pointer_set<tag>;
+    static auto mark() noexcept -> pointer_set<top>;
 
-    static auto mark(tag const* const, pointer_set<tag> &) noexcept -> void;
+    static auto mark(top const* const, pointer_set<top> &) noexcept -> void;
 
-    static auto sweep(pointer_set<tag> &&) -> void;
+    static auto sweep(pointer_set<top> &&) -> void;
   };
 
   static collector default_collector {};
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index af075c7c3..4fe1c7993 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -97,13 +97,9 @@ inline namespace memory
     template <typename Bound, typename Allocator, typename... Us>
     static auto make(Us&&... xs) -> gc_pointer
     {
-      if constexpr (std::is_same_v<Bound, Top>)
+      if constexpr (std::is_class_v<Bound>)
       {
-        return collector::make<Top, Allocator>(std::forward<decltype(xs)>(xs)...);
-      }
-      else if constexpr (std::is_class_v<Bound>)
-      {
-        return collector::make<collector::binder<Top, Bound>, Allocator>(std::forward<decltype(xs)>(xs)...);
+        return collector::make<collector::binder<Top, Bound, std::allocator_traits<Allocator>>, Allocator>(std::forward<decltype(xs)>(xs)...);
       }
       else
       {
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
index f6edd7460..98eb63ace 100644
--- a/src/memory/collector.cpp
+++ b/src/memory/collector.cpp
@@ -48,10 +48,10 @@ inline namespace memory
 
   auto collector::clear() -> void
   {
-    for (auto&& tag : tags)
+    for (auto&& object : objects)
     {
-      delete tag;
-      tags.erase(tag);
+      delete object;
+      objects.erase(object);
     }
   }
 
@@ -64,7 +64,7 @@ inline namespace memory
 
   auto collector::count() noexcept -> std::size_t
   {
-    return tags.size();
+    return objects.size();
   }
 
   auto collector::dlclose(void * const handle) -> void
@@ -112,9 +112,9 @@ inline namespace memory
     }
   }
 
-  auto collector::mark() noexcept -> pointer_set<tag>
+  auto collector::mark() noexcept -> pointer_set<top>
   {
-    auto is_root_object = [begin = tags.begin()](mutator const* given) // TODO INEFFICIENT!
+    auto is_root_object = [begin = objects.begin()](mutator const* given) // TODO INEFFICIENT!
     {
       /*
          If the given mutator is a non-root object, then an object containing
@@ -122,60 +122,63 @@ inline namespace memory
 
          Containing the mutator as a data member means that the address of the
          mutator is contained in the interval of the object's base-address ~
-         base-address + object-size. The tag is present to keep track of the
+         base-address + object-size. The top is present to keep track of the
          base-address and size of the object needed here.
       */
-      auto iter = tags.lower_bound(reinterpret_cast<tag const*>(given));
+      auto iter = objects.lower_bound(reinterpret_cast<top const*>(given));
 
       return iter == begin or not (*--iter)->contains(given);
     };
 
-    auto marked_tags = pointer_set<tag>();
+    auto marked_objects = pointer_set<top>();
 
     for (auto&& mutator : mutators)
     {
       assert(mutator);
       assert(mutator->object);
 
-      if (not marked_tags.contains(mutator->object) and is_root_object(mutator))
+      if (not marked_objects.contains(mutator->object) and is_root_object(mutator))
       {
-        mark(mutator->object, marked_tags);
+        mark(mutator->object, marked_objects);
       }
     }
 
-    return marked_tags;
+    return marked_objects;
   }
 
-  auto collector::mark(tag const* const object, pointer_set<tag> & marked_tags) noexcept -> void
+  auto collector::mark(top const* const object, pointer_set<top> & marked_objects) noexcept -> void
   {
     assert(object);
 
-    assert(tags.contains(object));
+    assert(objects.contains(object));
 
-    if (not marked_tags.contains(object))
+    if (not marked_objects.contains(object))
     {
-      marked_tags.insert(object);
+      marked_objects.insert(object);
 
-      for (auto each : *object)
+      auto lower = mutators.lower_bound(reinterpret_cast<mutator const*>(object->lower()));
+      auto upper = mutators.lower_bound(reinterpret_cast<mutator const*>(object->upper()));
+
+      for (; lower != upper; ++lower)
       {
-        mark(each->object, marked_tags);
+        mark((*lower)->object, marked_objects);
       }
     }
   }
 
-  auto collector::sweep(pointer_set<tag> && marked_tags) -> void
+  auto collector::sweep(pointer_set<top> && marked_objects) -> void
   {
-    for (auto marked_tag : marked_tags)
+    for (auto marked_object : marked_objects)
     {
-      tags.erase(marked_tag);
+      objects.erase(marked_object);
     }
 
-    for (auto tag : tags)
+    for (auto object : objects)
     {
-      delete tag;
+      delete object;
     }
 
-    tags.swap(marked_tags);
+    objects.swap(marked_objects);
   }
 } // namespace memory
 } // namespace meevax

From 03e0b8b0739ba9b53616968f54601ab783e4cba2 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Fri, 22 Mar 2024 23:58:54 +0900
Subject: [PATCH 32/40] Remove static member function `mutator::locate`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                             |  6 ++---
 VERSION                               |  2 +-
 include/meevax/memory/collector.hpp   | 37 +++++----------------------
 include/meevax/memory/gc_pointer.hpp  |  8 +++---
 include/meevax/memory/integer_set.hpp |  6 +++--
 5 files changed, 18 insertions(+), 41 deletions(-)

diff --git a/README.md b/README.md
index e8f194644..cbfe39463 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.150_amd64.deb
+sudo apt install build/meevax_0.5.151_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.150.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.151.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.150_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.151_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 5a23fcf60..ad41454f0 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.150
+0.5.151
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 7302b9197..8fb8b9791 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -160,7 +160,7 @@ inline namespace memory
     protected:
       top const* object = nullptr;
 
-      constexpr mutator() = default;
+      mutator() = default;
 
       explicit mutator(top const* object) noexcept
         : object { object }
@@ -173,41 +173,18 @@ inline namespace memory
 
       ~mutator() noexcept
       {
-        if (object)
-        {
-          mutators.erase(this);
-        }
+        mutators.erase(this);
       }
 
       auto reset(top const* after = nullptr) noexcept -> void
       {
-        if (auto before = std::exchange(object, after); not before and after)
+        if (object = after; after)
         {
           mutators.insert(this);
         }
-        else if (before and not after)
-        {
-          mutators.erase(this);
-        }
-      }
-
-      static auto locate(void const* const data) noexcept -> top const*
-      {
-        if (not data)
-        {
-          return nullptr;
-        }
-        else if (cache->contains(data))
-        {
-          return cache;
-        }
-        else if (auto iter = objects.lower_bound(reinterpret_cast<top const*>(data)); iter != objects.begin() and (*--iter)->contains(data))
-        {
-          return *iter;
-        }
         else
         {
-          return nullptr;
+          mutators.erase(this);
         }
       }
     };
@@ -222,8 +199,6 @@ inline namespace memory
     using pointer_set = integer_set<T const*, 15, 16, 16>;
 
   private:
-    static inline top * cache = nullptr;
-
     static inline pointer_set<top> objects {};
 
     static inline pointer_set<mutator> mutators {};
@@ -247,7 +222,7 @@ inline namespace memory
 
     auto operator =(collector const&) -> collector & = delete;
 
-    template <typename T, typename Allocator = default_allocator<void>, typename... Ts>
+    template <typename T, typename... Ts>
     static auto make(Ts&&... xs)
     {
       static_assert(std::is_base_of_v<top, T>);
@@ -259,7 +234,7 @@ inline namespace memory
 
       if (auto data = new T(std::forward<decltype(xs)>(xs)...); data)
       {
-        objects.insert(cache = data);
+        objects.insert(data);
 
         return data;
       }
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index 4fe1c7993..259a63ad2 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -40,7 +40,7 @@ inline namespace memory
 
     gc_pointer(base_pointer const& p)
       : base_pointer { p }
-      , collector::mutator { locate(base_pointer::get()) }
+      , collector::mutator { base_pointer::get() }
     {}
 
     gc_pointer(std::nullptr_t = nullptr)
@@ -48,7 +48,7 @@ inline namespace memory
 
     gc_pointer(Top * top) // TODO Top const*
       : base_pointer { top }
-      , collector::mutator { locate(base_pointer::get()) }
+      , collector::mutator { base_pointer::get() }
     {}
 
     template <typename T, typename = std::enable_if_t<(std::is_same_v<T, Ts> or ... or std::is_same_v<T, double>)>>
@@ -85,7 +85,7 @@ inline namespace memory
     auto reset(base_pointer const& p) -> void
     {
       base_pointer::reset(p);
-      collector::mutator::reset(locate(base_pointer::get()));
+      collector::mutator::reset(base_pointer::get());
     }
 
     auto reset(std::nullptr_t = nullptr) -> void
@@ -99,7 +99,7 @@ inline namespace memory
     {
       if constexpr (std::is_class_v<Bound>)
       {
-        return collector::make<collector::binder<Top, Bound, std::allocator_traits<Allocator>>, Allocator>(std::forward<decltype(xs)>(xs)...);
+        return collector::make<collector::binder<Top, Bound, std::allocator_traits<Allocator>>>(std::forward<decltype(xs)>(xs)...);
       }
       else
       {
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index fa8c8b52e..b26f2f816 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -216,8 +216,10 @@ inline namespace memory
 
     auto erase(T value) noexcept
     {
-      auto [i, j] = split(value);
-      data[i]->erase(j);
+      if (auto [i, j] = split(value); data[i])
+      {
+        data[i]->erase(j);
+      }
     }
 
     auto contains(T value) noexcept -> bool

From a361587c2f7c24bd1afee2be2f9d34f14dbcdc3a Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 23 Mar 2024 02:05:32 +0900
Subject: [PATCH 33/40] Update `collector` to a template class

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                            |   6 +-
 VERSION                              |   2 +-
 include/meevax/kernel/pair.hpp       |  10 +-
 include/meevax/memory/collector.hpp  | 162 ++++++++++++++++++++---
 include/meevax/memory/gc_pointer.hpp |  20 +--
 src/kernel/boot.cpp                  |   4 +-
 src/memory/collector.cpp             | 184 ---------------------------
 test/collector.cpp                   |  86 ++++++-------
 test/environment.cpp                 |   6 +-
 test/vector.cpp                      |  74 +++++------
 10 files changed, 249 insertions(+), 305 deletions(-)
 delete mode 100644 src/memory/collector.cpp

diff --git a/README.md b/README.md
index cbfe39463..e70210c2a 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.151_amd64.deb
+sudo apt install build/meevax_0.5.152_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.151.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.152.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.151_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.152_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index ad41454f0..df008cbd4 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.151
+0.5.152
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 322473b69..0879c2a10 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -30,6 +30,8 @@ inline namespace kernel
 
   struct pair;
 
+  using default_collector = collector<pair, bool, int, float, character, instruction>;
+
   using object = gc_pointer<pair, bool, int, float, character, instruction>;
 
   using let = object;
@@ -48,19 +50,19 @@ inline namespace kernel
     if constexpr (std::is_same_v<T, pair>) {
       return object::make<T, simple_allocator<void>>(std::forward<decltype(xs)>(xs)...);
     } else {
-      return object::make<T, collector::default_allocator<void>>(std::forward<decltype(xs)>(xs)...);
+      return object::make<T, default_allocator<void>>(std::forward<decltype(xs)>(xs)...);
     }
   }
 
   template <typename T,
-            typename Allocator = collector::default_allocator<void>>
+            typename Allocator = default_allocator<void>>
   auto make(T&& x) -> decltype(auto)
   {
     return object::make<std::decay_t<T>, Allocator>(std::forward<decltype(x)>(x));
   }
 
   template <template <typename...> typename Traits,
-            typename Allocator = collector::default_allocator<void>,
+            typename Allocator = default_allocator<void>,
             typename... Ts,
             REQUIRES(std::is_constructible<typename Traits<Ts...>::type, Ts...>)>
   auto make(Ts&&... xs) -> decltype(auto)
@@ -68,7 +70,7 @@ inline namespace kernel
     return make<typename Traits<Ts...>::type, Allocator>(std::forward<decltype(xs)>(xs)...);
   }
 
-  struct pair : public virtual collector::top
+  struct pair : public virtual default_collector::top
               , public std::pair<object, object>
   {
     template <auto Const>
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 8fb8b9791..ab8a712dc 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -17,6 +17,12 @@
 #ifndef INCLUDED_MEEVAX_MEMORY_COLLECTOR_HPP
 #define INCLUDED_MEEVAX_MEMORY_COLLECTOR_HPP
 
+#if __unix__
+#include <dlfcn.h> // dlopen, dlclose, dlerror
+#else
+#error
+#endif
+
 #include <cstddef> // std::size_t
 #include <memory> // std::allocator
 #include <unordered_map>
@@ -32,6 +38,9 @@ namespace meevax
 {
 inline namespace memory
 {
+  template <typename... Ts>
+  using default_allocator = std::allocator<Ts...>;
+
   /*
      This mark-and-sweep garbage collector is based on the implementation of
      gc_ptr written by William E. Kempf and posted to CodeProject.
@@ -39,6 +48,7 @@ inline namespace memory
      - https://www.codeproject.com/Articles/912/A-garbage-collection-framework-for-C
      - https://www.codeproject.com/Articles/938/A-garbage-collection-framework-for-C-Part-II
   */
+  template <typename Top, typename... Ts>
   class collector
   {
   public:
@@ -64,11 +74,11 @@ inline namespace memory
 
     static inline auto cleared = false;
 
-    template <typename Top, typename Bound, typename AllocatorTraits = std::allocator_traits<std::allocator<void>>>
+    template <typename Bound, typename AllocatorTraits = std::allocator_traits<std::allocator<void>>>
     struct binder : public virtual std::conditional_t<std::is_same_v<Top, Bound>, top, Top>
                   , public Bound
     {
-      struct allocator_type : public AllocatorTraits::template rebind_alloc<binder<Top, Bound, AllocatorTraits>>
+      struct allocator_type : public AllocatorTraits::template rebind_alloc<binder<Bound, AllocatorTraits>>
       {
         ~allocator_type()
         {
@@ -189,9 +199,6 @@ inline namespace memory
       }
     };
 
-    template <typename... Ts>
-    using default_allocator = std::allocator<Ts...>;
-
     /*
        0x0000'0000'0000'0000 ~ 0x7FFF'FFFF'FFFF'FFFF
     */
@@ -210,20 +217,20 @@ inline namespace memory
     static inline std::unordered_map<std::string, std::unique_ptr<void, void (*)(void * const)>> dynamic_linked_libraries {};
 
   public:
-    collector();
+    collector() = delete;
 
     collector(collector &&) = delete;
 
     collector(collector const&) = delete;
 
-    ~collector();
+    ~collector() = delete;
 
     auto operator =(collector &&) -> collector & = delete;
 
     auto operator =(collector const&) -> collector & = delete;
 
-    template <typename T, typename... Ts>
-    static auto make(Ts&&... xs)
+    template <typename T, typename... Us>
+    static auto make(Us&&... xs)
     {
       static_assert(std::is_base_of_v<top, T>);
 
@@ -244,26 +251,141 @@ inline namespace memory
       }
     }
 
-    static auto clear() -> void;
+    static auto clear() -> void
+    {
+      for (auto&& object : objects)
+      {
+        delete object;
+        objects.erase(object);
+      }
+    }
 
-    static auto collect() -> void;
+    static auto collect() -> void
+    {
+      allocation = 0;
 
-    static auto count() noexcept -> std::size_t;
+      return sweep(mark());
+    }
 
-    static auto dlclose(void * const) -> void;
+    static auto count() noexcept -> std::size_t
+    {
+      return objects.size();
+    }
 
-    static auto dlopen(std::string const&) -> void *;
+    static auto dlclose(void * const handle) -> void
+    {
+      if (handle and ::dlclose(handle))
+      {
+        std::cerr << ::dlerror() << std::endl;
+      }
+    }
 
-    static auto dlsym(std::string const&, void * const) -> void *;
+    static auto dlopen(std::string const& filename) -> void *
+    {
+      ::dlerror(); // Clear
 
-    static auto mark() noexcept -> pointer_set<top>;
+      try
+      {
+        return dynamic_linked_libraries.at(filename).get();
+      }
+      catch (std::out_of_range const&)
+      {
+        if (auto handle = ::dlopen(filename.c_str(), RTLD_LAZY | RTLD_GLOBAL); handle)
+        {
+          dynamic_linked_libraries.emplace(std::piecewise_construct,
+                                           std::forward_as_tuple(filename),
+                                           std::forward_as_tuple(handle, dlclose));
 
-    static auto mark(top const* const, pointer_set<top> &) noexcept -> void;
+          return dlopen(filename);
+        }
+        else
+        {
+          throw std::runtime_error(::dlerror());
+        }
+      }
+    }
 
-    static auto sweep(pointer_set<top> &&) -> void;
-  };
+    static auto dlsym(std::string const& symbol, void * const handle) -> void *
+    {
+      if (auto address = ::dlsym(handle, symbol.c_str()); address)
+      {
+        return address;
+      }
+      else
+      {
+        throw std::runtime_error(::dlerror());
+      }
+    }
 
-  static collector default_collector {};
+    static auto mark() noexcept -> pointer_set<top>
+    {
+      auto is_root_object = [begin = objects.begin()](mutator const* given) // TODO INEFFICIENT!
+      {
+        /*
+           If the given mutator is a non-root object, then an object containing
+           this mutator as a data member exists somewhere in memory.
+
+           Containing the mutator as a data member means that the address of
+           the mutator is contained in the interval of the object's
+           base-address ~ base-address + object-size. The top is present to
+           keep track of the base-address and size of the object needed here.
+        */
+        auto iter = objects.lower_bound(reinterpret_cast<top const*>(given));
+
+        return iter == begin or not (*--iter)->contains(given);
+      };
+
+      auto marked_objects = pointer_set<top>();
+
+      for (auto&& mutator : mutators)
+      {
+        assert(mutator);
+        assert(mutator->object);
+
+        if (not marked_objects.contains(mutator->object) and is_root_object(mutator))
+        {
+          mark(mutator->object, marked_objects);
+        }
+      }
+
+      return marked_objects;
+    }
+
+    static auto mark(top const* const object, pointer_set<top> & marked_objects) noexcept -> void
+    {
+      assert(object);
+
+      assert(objects.contains(object));
+
+      if (not marked_objects.contains(object))
+      {
+        marked_objects.insert(object);
+
+        auto lower = mutators.lower_bound(reinterpret_cast<mutator const*>(object->lower()));
+        auto upper = mutators.lower_bound(reinterpret_cast<mutator const*>(object->upper()));
+
+        for (; lower != upper; ++lower)
+        {
+          mark((*lower)->object, marked_objects);
+        }
+      }
+    }
+
+    static auto sweep(pointer_set<top> && marked_objects) -> void
+    {
+      for (auto marked_object : marked_objects)
+      {
+        objects.erase(marked_object);
+      }
+
+      for (auto object : objects)
+      {
+        delete object;
+      }
+
+      objects.swap(marked_objects);
+    }
+  };
 } // namespace memory
 } // namespace meevax
 
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
index 259a63ad2..05403cc2d 100644
--- a/include/meevax/memory/gc_pointer.hpp
+++ b/include/meevax/memory/gc_pointer.hpp
@@ -29,18 +29,18 @@ inline namespace memory
 {
   template <typename Top, typename... Ts>
   struct gc_pointer : public nan_boxing_pointer<Top, Ts...>
-                    , private collector::mutator
+                    , private collector<Top, Ts...>::mutator
   {
     using base_pointer = nan_boxing_pointer<Top, Ts...>;
 
     gc_pointer(gc_pointer const& gcp)
       : base_pointer { gcp }
-      , collector::mutator { gcp.object }
+      , collector<Top, Ts...>::mutator { gcp.object }
     {}
 
     gc_pointer(base_pointer const& p)
       : base_pointer { p }
-      , collector::mutator { base_pointer::get() }
+      , collector<Top, Ts...>::mutator { base_pointer::get() }
     {}
 
     gc_pointer(std::nullptr_t = nullptr)
@@ -48,7 +48,7 @@ inline namespace memory
 
     gc_pointer(Top * top) // TODO Top const*
       : base_pointer { top }
-      , collector::mutator { base_pointer::get() }
+      , collector<Top, Ts...>::mutator { base_pointer::get() }
     {}
 
     template <typename T, typename = std::enable_if_t<(std::is_same_v<T, Ts> or ... or std::is_same_v<T, double>)>>
@@ -79,19 +79,19 @@ inline namespace memory
     auto reset(gc_pointer const& gcp) -> void
     {
       base_pointer::reset(gcp);
-      collector::mutator::reset(gcp.object);
+      collector<Top, Ts...>::mutator::reset(gcp.object);
     }
 
     auto reset(base_pointer const& p) -> void
     {
       base_pointer::reset(p);
-      collector::mutator::reset(base_pointer::get());
+      collector<Top, Ts...>::mutator::reset(base_pointer::get());
     }
 
     auto reset(std::nullptr_t = nullptr) -> void
     {
       base_pointer::reset();
-      collector::mutator::reset();
+      collector<Top, Ts...>::mutator::reset();
     }
 
     template <typename Bound, typename Allocator, typename... Us>
@@ -99,7 +99,11 @@ inline namespace memory
     {
       if constexpr (std::is_class_v<Bound>)
       {
-        return collector::make<collector::binder<Top, Bound, std::allocator_traits<Allocator>>>(std::forward<decltype(xs)>(xs)...);
+        return collector<Top, Ts...>::template make<
+                 typename collector<Top, Ts...>::template binder<
+                   Bound, std::allocator_traits<Allocator>>>(
+                     std::forward<decltype(xs)>(xs)...
+                     );
       }
       else
       {
diff --git a/src/kernel/boot.cpp b/src/kernel/boot.cpp
index 5de22f54e..3462a5bfc 100644
--- a/src/kernel/boot.cpp
+++ b/src/kernel/boot.cpp
@@ -1322,8 +1322,8 @@ inline namespace kernel
       {
         return make<procedure>(cadr(xs).as<symbol>(),
                                reinterpret_cast<primitive_procedure::signature>(
-                                 collector::dlsym(cadr(xs).as<symbol>(),
-                                                  collector::dlopen(car(xs).as<string>()))));
+                                 default_collector::dlsym(cadr(xs).as<symbol>(),
+                                                          default_collector::dlopen(car(xs).as<string>()))));
       });
     });
 
diff --git a/src/memory/collector.cpp b/src/memory/collector.cpp
deleted file mode 100644
index 98eb63ace..000000000
--- a/src/memory/collector.cpp
+++ /dev/null
@@ -1,184 +0,0 @@
-/*
-   Copyright 2018-2023 Tatsuya Yamasaki.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-#if __unix__
-#include <dlfcn.h> // dlopen, dlclose, dlerror
-#else
-#error
-#endif
-
-#include <iostream>
-
-#include <meevax/memory/collector.hpp>
-#include <meevax/memory/literal.hpp>
-
-namespace meevax
-{
-inline namespace memory
-{
-  static auto reference_count = 0;
-
-  collector::collector()
-  {
-    if (not reference_count++)
-    {
-    }
-  }
-
-  collector::~collector()
-  {
-    if (not --reference_count)
-    {
-      clear();
-    }
-  }
-
-  auto collector::clear() -> void
-  {
-    for (auto&& object : objects)
-    {
-      delete object;
-      objects.erase(object);
-    }
-  }
-
-  auto collector::collect() -> void
-  {
-    allocation = 0;
-
-    return sweep(mark());
-  }
-
-  auto collector::count() noexcept -> std::size_t
-  {
-    return objects.size();
-  }
-
-  auto collector::dlclose(void * const handle) -> void
-  {
-    if (handle and ::dlclose(handle))
-    {
-      std::cerr << ::dlerror() << std::endl;
-    }
-  }
-
-  auto collector::dlopen(std::string const& filename) -> void *
-  {
-    ::dlerror(); // Clear
-
-    try
-    {
-      return dynamic_linked_libraries.at(filename).get();
-    }
-    catch (std::out_of_range const&)
-    {
-      if (auto handle = ::dlopen(filename.c_str(), RTLD_LAZY | RTLD_GLOBAL); handle)
-      {
-        dynamic_linked_libraries.emplace(std::piecewise_construct,
-                                         std::forward_as_tuple(filename),
-                                         std::forward_as_tuple(handle, dlclose));
-
-        return dlopen(filename);
-      }
-      else
-      {
-        throw std::runtime_error(::dlerror());
-      }
-    }
-  }
-
-  auto collector::dlsym(std::string const& symbol, void * const handle) -> void *
-  {
-    if (auto address = ::dlsym(handle, symbol.c_str()); address)
-    {
-      return address;
-    }
-    else
-    {
-      throw std::runtime_error(::dlerror());
-    }
-  }
-
-  auto collector::mark() noexcept -> pointer_set<top>
-  {
-    auto is_root_object = [begin = objects.begin()](mutator const* given) // TODO INEFFICIENT!
-    {
-      /*
-         If the given mutator is a non-root object, then an object containing
-         this mutator as a data member exists somewhere in memory.
-
-         Containing the mutator as a data member means that the address of the
-         mutator is contained in the interval of the object's base-address ~
-         base-address + object-size. The top is present to keep track of the
-         base-address and size of the object needed here.
-      */
-      auto iter = objects.lower_bound(reinterpret_cast<top const*>(given));
-
-      return iter == begin or not (*--iter)->contains(given);
-    };
-
-    auto marked_objects = pointer_set<top>();
-
-    for (auto&& mutator : mutators)
-    {
-      assert(mutator);
-      assert(mutator->object);
-
-      if (not marked_objects.contains(mutator->object) and is_root_object(mutator))
-      {
-        mark(mutator->object, marked_objects);
-      }
-    }
-
-    return marked_objects;
-  }
-
-  auto collector::mark(top const* const object, pointer_set<top> & marked_objects) noexcept -> void
-  {
-    assert(object);
-
-    assert(objects.contains(object));
-
-    if (not marked_objects.contains(object))
-    {
-      marked_objects.insert(object);
-
-      auto lower = mutators.lower_bound(reinterpret_cast<mutator const*>(object->lower()));
-      auto upper = mutators.lower_bound(reinterpret_cast<mutator const*>(object->upper()));
-
-      for (; lower != upper; ++lower)
-      {
-        mark((*lower)->object, marked_objects);
-      }
-    }
-  }
-
-  auto collector::sweep(pointer_set<top> && marked_objects) -> void
-  {
-    for (auto marked_object : marked_objects)
-    {
-      objects.erase(marked_object);
-    }
-
-    for (auto object : objects)
-    {
-      delete object;
-    }
-
-    objects.swap(marked_objects);
-  }
-} // namespace memory
-} // namespace meevax
diff --git a/test/collector.cpp b/test/collector.cpp
index 4a763d90e..6e69055df 100644
--- a/test/collector.cpp
+++ b/test/collector.cpp
@@ -7,7 +7,7 @@ auto main() -> int
 {
   using namespace meevax;
 
-  const auto gc_count = default_collector.count();
+  const auto gc_count = default_collector::count();
 
   // scope
   {
@@ -16,19 +16,19 @@ auto main() -> int
       let y = make<symbol>("y");
       let z = make<symbol>("z");
 
-      assert(default_collector.count() == gc_count + 3);
-      default_collector.collect();
-      assert(default_collector.count() == gc_count + 3);
+      assert(default_collector::count() == gc_count + 3);
+      default_collector::collect();
+      assert(default_collector::count() == gc_count + 3);
     }
 
-    assert(default_collector.count() == gc_count + 3);
-    default_collector.collect();
-    assert(default_collector.count() == gc_count);
+    assert(default_collector::count() == gc_count + 3);
+    default_collector::collect();
+    assert(default_collector::count() == gc_count);
   }
 
-  assert(default_collector.count() == gc_count);
-  default_collector.collect();
-  assert(default_collector.count() == gc_count);
+  assert(default_collector::count() == gc_count);
+  default_collector::collect();
+  assert(default_collector::count() == gc_count);
 
   // copy
   {
@@ -42,9 +42,9 @@ auto main() -> int
     assert(eqv(x, y));
   }
 
-  assert(default_collector.count() == gc_count + 1);
-  default_collector.collect();
-  assert(default_collector.count() == gc_count);
+  assert(default_collector::count() == gc_count + 1);
+  default_collector::collect();
+  assert(default_collector::count() == gc_count);
 
   // move
   {
@@ -63,17 +63,17 @@ auto main() -> int
     assert(x.is<symbol>());
     assert(x.as<symbol>() == "x");
 
-    assert(default_collector.count() == gc_count + 1);
-    default_collector.collect();
-    assert(default_collector.count() == gc_count + 1);
+    assert(default_collector::count() == gc_count + 1);
+    default_collector::collect();
+    assert(default_collector::count() == gc_count + 1);
 
     assert(x.is<symbol>());
     assert(x.as<symbol>() == "x");
   }
 
-  assert(default_collector.count() == gc_count + 1);
-  default_collector.collect();
-  assert(default_collector.count() == gc_count);
+  assert(default_collector::count() == gc_count + 1);
+  default_collector::collect();
+  assert(default_collector::count() == gc_count);
 
   // proper list
   {
@@ -91,9 +91,9 @@ auto main() -> int
       assert(y.as<symbol>() == "y");
       assert(z.as<symbol>() == "z");
 
-      assert(default_collector.count() == gc_count + 3);
-      default_collector.collect();
-      assert(default_collector.count() == gc_count + 3);
+      assert(default_collector::count() == gc_count + 3);
+      default_collector::collect();
+      assert(default_collector::count() == gc_count + 3);
 
       return list(x, y, z);
     };
@@ -106,9 +106,9 @@ auto main() -> int
     assert(cadr(a).is<symbol>());
     assert(caddr(a).is<symbol>());
 
-    assert(default_collector.count() == gc_count + 6);
-    default_collector.collect();
-    assert(default_collector.count() == gc_count + 6);
+    assert(default_collector::count() == gc_count + 6);
+    default_collector::collect();
+    assert(default_collector::count() == gc_count + 6);
 
     assert(length(a) == 3);
 
@@ -117,9 +117,9 @@ auto main() -> int
     assert(caddr(a).is<symbol>());
   }
 
-  assert(default_collector.count() == gc_count + 6);
-  default_collector.collect();
-  assert(default_collector.count() == gc_count);
+  assert(default_collector::count() == gc_count + 6);
+  default_collector::collect();
+  assert(default_collector::count() == gc_count);
 
   // improper list
   {
@@ -137,7 +137,7 @@ auto main() -> int
       assert(b.as<symbol>() == "b");
       assert(c.as<symbol>() == "c");
 
-      assert(default_collector.count() == gc_count + 3);
+      assert(default_collector::count() == gc_count + 3);
 
       return circular_list(a, b, c);
     };
@@ -149,7 +149,7 @@ auto main() -> int
     assert(caddr(x).as<symbol>() == "c");
     assert(cadddr(x).as<symbol>() == "a");
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(car(x).as<symbol>() == "a");
     assert(cadr(x).as<symbol>() == "b");
@@ -157,28 +157,28 @@ auto main() -> int
     assert(cadddr(x).as<symbol>() == "a");
   }
 
-  default_collector.collect();
+  default_collector::collect();
 
   // change class
   {
     let x = make<symbol>("hoge");
 
-    default_collector.collect();
+    default_collector::collect();
 
-    assert(default_collector.count() == gc_count + 1);
+    assert(default_collector::count() == gc_count + 1);
     assert(x.is<symbol>());
     assert(x.as<symbol>() == "hoge");
 
     x = make<exact_integer>(42);
 
-    default_collector.collect();
+    default_collector::collect();
 
-    assert(default_collector.count() == gc_count + 1);
+    assert(default_collector::count() == gc_count + 1);
     assert(x.is<exact_integer>());
     assert(x.as<exact_integer>() == 42);
   }
 
-  default_collector.collect();
+  default_collector::collect();
 
   // number
   {
@@ -194,22 +194,22 @@ auto main() -> int
       assert(y.as<double>() == 42);
     }
 
-    assert(default_collector.count() == gc_count);
-    default_collector.collect();
-    assert(default_collector.count() == gc_count);
+    assert(default_collector::count() == gc_count);
+    default_collector::collect();
+    assert(default_collector::count() == gc_count);
   }
 
-  default_collector.collect();
+  default_collector::collect();
 
   // read list
   {
-    const auto gc_count = default_collector.count();
+    const auto gc_count = default_collector::count();
 
     input_string_port("(a a a)").read();
 
-    default_collector.collect();
+    default_collector::collect();
 
-    assert(default_collector.count() == gc_count + 1);
+    assert(default_collector::count() == gc_count + 1);
   }
 
   return EXIT_SUCCESS;
diff --git a/test/environment.cpp b/test/environment.cpp
index 3e0a0957b..3c59cea9b 100644
--- a/test/environment.cpp
+++ b/test/environment.cpp
@@ -21,7 +21,7 @@ auto main() -> int
     assert(interaction_environment().is<environment>());
   }
 
-  const auto gc_count = default_collector.count();
+  const auto gc_count = default_collector::count();
 
   assert(gc_count == specials_count);
 
@@ -38,9 +38,9 @@ auto main() -> int
 
   assert(libraries().empty());
 
-  default_collector.collect();
+  default_collector::collect();
 
-  assert(gc_count - 1 == default_collector.count()); // -1 is interaction_environment
+  assert(gc_count - 1 == default_collector::count()); // -1 is interaction_environment
 
   return EXIT_SUCCESS;
 }
diff --git a/test/vector.cpp b/test/vector.cpp
index ef5cac3f4..c77622f30 100644
--- a/test/vector.cpp
+++ b/test/vector.cpp
@@ -8,45 +8,45 @@ auto main() -> int
 {
   using namespace meevax;
 
-  const auto gc_count = default_collector.count();
+  const auto gc_count = default_collector::count();
 
   // make-vector
   {
     let const v = make<vector>(list(make<symbol>("a"),
                                     make<symbol>("b"),
                                     make<symbol>("c")));
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(default_collector.count() == gc_count + 1);
+    assert(default_collector::count() == gc_count + 1);
   }
 
-  default_collector.collect();
+  default_collector::collect();
 
   // list->vector
   {
@@ -56,38 +56,38 @@ auto main() -> int
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 7);
+    assert(default_collector::count() == gc_count + 7);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(default_collector.count() == gc_count + 1);
+    assert(default_collector::count() == gc_count + 1);
   }
 
-  default_collector.collect();
+  default_collector::collect();
 
   // list->vector
   {
-    auto const gc_count = default_collector.count();
+    auto const gc_count = default_collector::count();
 
     let const v = make<vector>(input_string_port("(a b c)").read());
 
@@ -97,31 +97,31 @@ auto main() -> int
     assert(v.as<vector>().vector[1].as<symbol>() == "b");
     assert(v.as<vector>().vector[2].as<symbol>() == "c");
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
     assert(v.as<vector>().vector[0].as<symbol>() == "a");
     assert(v.as<vector>().vector[1].as<symbol>() == "b");
     assert(v.as<vector>().vector[2].as<symbol>() == "c");
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
     assert(v.as<vector>().vector[0].as<symbol>() == "a");
     assert(v.as<vector>().vector[1].as<symbol>() == "b");
     assert(v.as<vector>().vector[2].as<symbol>() == "c");
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
@@ -129,45 +129,45 @@ auto main() -> int
 
   symbols().clear();
 
-  default_collector.collect();
+  default_collector::collect();
 
   // vector literal
   {
-    auto const gc_count = default_collector.count();
+    auto const gc_count = default_collector::count();
 
     let const v = input_string_port("#(a b c)").read();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 3);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
     v.as<vector>().vector.clear();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
 
-    default_collector.collect();
+    default_collector::collect();
 
     assert(v.is<vector>());
     assert(v.as<vector>().vector.size() == 0);
-    assert(default_collector.count() == gc_count + 4);
+    assert(default_collector::count() == gc_count + 4);
   }
 
   symbols().clear();
 
-  default_collector.collect();
+  default_collector::collect();
 
   // vector constructor
   {

From 7670948646f2c952ad4f4f1f110b1a9f1b046c5f Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 23 Mar 2024 02:24:46 +0900
Subject: [PATCH 34/40] Move class `gc_pointer` into class `collector`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                            |   6 +-
 VERSION                              |   2 +-
 include/meevax/kernel/pair.hpp       |   4 +-
 include/meevax/memory/collector.hpp  | 225 +++++++++++++++++++++++-
 include/meevax/memory/gc_pointer.hpp | 254 ---------------------------
 5 files changed, 230 insertions(+), 261 deletions(-)
 delete mode 100644 include/meevax/memory/gc_pointer.hpp

diff --git a/README.md b/README.md
index e70210c2a..50cc40c32 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.152_amd64.deb
+sudo apt install build/meevax_0.5.153_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.152.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.153.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.152_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.153_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index df008cbd4..04b5f01f1 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.152
+0.5.153
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 0879c2a10..8dca367df 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -20,7 +20,7 @@
 #include <meevax/functional/compose.hpp>
 #include <meevax/kernel/character.hpp>
 #include <meevax/kernel/instruction.hpp>
-#include <meevax/memory/gc_pointer.hpp>
+#include <meevax/memory/collector.hpp>
 
 namespace meevax
 {
@@ -32,7 +32,7 @@ inline namespace kernel
 
   using default_collector = collector<pair, bool, int, float, character, instruction>;
 
-  using object = gc_pointer<pair, bool, int, float, character, instruction>;
+  using object = default_collector::gc_pointer;
 
   using let = object;
 
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index ab8a712dc..09649eec7 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -23,16 +23,18 @@
 #error
 #endif
 
-#include <cstddef> // std::size_t
 #include <memory> // std::allocator
 #include <unordered_map>
 
 #include <meevax/iostream/escape_sequence.hpp>
+#include <meevax/iostream/lexical_cast.hpp>
 #include <meevax/memory/integer_set.hpp>
 #include <meevax/memory/literal.hpp>
+#include <meevax/memory/nan_boxing_pointer.hpp>
 #include <meevax/memory/simple_allocator.hpp>
 #include <meevax/type_traits/is_equality_comparable.hpp>
 #include <meevax/type_traits/is_output_streamable.hpp>
+#include <meevax/utility/demangle.hpp>
 
 namespace meevax
 {
@@ -199,6 +201,227 @@ inline namespace memory
       }
     };
 
+    struct gc_pointer : public nan_boxing_pointer<Top, Ts...>
+                      , private collector<Top, Ts...>::mutator
+    {
+      using base_pointer = nan_boxing_pointer<Top, Ts...>;
+
+      gc_pointer(gc_pointer const& gcp)
+        : base_pointer { gcp }
+        , collector<Top, Ts...>::mutator { gcp.object }
+      {}
+
+      gc_pointer(base_pointer const& p)
+        : base_pointer { p }
+        , collector<Top, Ts...>::mutator { base_pointer::get() }
+      {}
+
+      gc_pointer(std::nullptr_t = nullptr)
+      {}
+
+      gc_pointer(Top * top) // TODO Top const*
+        : base_pointer { top }
+        , collector<Top, Ts...>::mutator { base_pointer::get() }
+      {}
+
+      template <typename T, typename = std::enable_if_t<(std::is_same_v<T, Ts> or ... or std::is_same_v<T, double>)>>
+      gc_pointer(T const& datum)
+        : base_pointer { datum }
+      {
+        assert(base_pointer::get() == nullptr);
+      }
+
+      auto operator =(gc_pointer const& gcp) -> auto &
+      {
+        reset(gcp);
+        return *this;
+      }
+
+      auto operator =(base_pointer const& p) -> auto &
+      {
+        reset(p);
+        return *this;
+      }
+
+      auto operator =(std::nullptr_t) -> auto &
+      {
+        reset();
+        return *this;
+      }
+
+      auto reset(gc_pointer const& gcp) -> void
+      {
+        base_pointer::reset(gcp);
+        collector<Top, Ts...>::mutator::reset(gcp.object);
+      }
+
+      auto reset(base_pointer const& p) -> void
+      {
+        base_pointer::reset(p);
+        collector<Top, Ts...>::mutator::reset(base_pointer::get());
+      }
+
+      auto reset(std::nullptr_t = nullptr) -> void
+      {
+        base_pointer::reset();
+        collector<Top, Ts...>::mutator::reset();
+      }
+
+      template <typename Bound, typename Allocator, typename... Us>
+      static auto make(Us&&... xs) -> gc_pointer
+      {
+        if constexpr (std::is_class_v<Bound>)
+        {
+          return collector<Top, Ts...>::template make<
+                   typename collector<Top, Ts...>::template binder<
+                     Bound, std::allocator_traits<Allocator>>>(
+                       std::forward<decltype(xs)>(xs)...
+                       );
+        }
+        else
+        {
+          return { std::forward<decltype(xs)>(xs)... };
+        }
+      }
+
+      template <typename U>
+      inline auto as() const -> decltype(auto)
+      {
+        if constexpr (std::is_same_v<std::decay_t<U>, Top>)
+        {
+          return base_pointer::operator *();
+        }
+        else if constexpr (std::is_class_v<std::decay_t<U>>)
+        {
+          if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
+          {
+            return *data;
+          }
+          else
+          {
+            throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
+          }
+        }
+        else
+        {
+          return base_pointer::template as<U>();
+        }
+      }
+
+      template <typename U>
+      inline auto as() -> decltype(auto)
+      {
+        if constexpr (std::is_same_v<std::decay_t<U>, Top>)
+        {
+          return base_pointer::operator *();
+        }
+        else if constexpr (std::is_class_v<std::decay_t<U>>)
+        {
+          if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
+          {
+            return *data;
+          }
+          else
+          {
+            throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
+          }
+        }
+        else
+        {
+          return base_pointer::template as<U>();
+        }
+      }
+
+      template <typename U>
+      inline auto as_const() const -> decltype(auto)
+      {
+        return as<std::add_const_t<U>>();
+      }
+
+      inline auto compare(gc_pointer const& rhs) const -> bool
+      {
+        if (base_pointer::dereferenceable())
+        {
+          return *this ? base_pointer::get()->compare(rhs.get()) : rhs.is<std::nullptr_t>();
+        }
+        else
+        {
+          return base_pointer::compare(rhs);
+        }
+      }
+
+      template <typename U>
+      inline auto is() const
+      {
+        return type() == typeid(std::decay_t<U>);
+      }
+
+      template <typename U, REQUIRES(std::is_class<U>)>
+      inline auto is_also() const
+      {
+        return dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()) != nullptr;
+      }
+
+      inline auto type() const -> std::type_info const&
+      {
+        if (base_pointer::dereferenceable())
+        {
+          return *this ? base_pointer::get()->type() : typeid(std::nullptr_t);
+        }
+        else
+        {
+          return base_pointer::type();
+        }
+      }
+
+      inline auto write(std::ostream & os) const -> std::ostream &
+      {
+        if (base_pointer::dereferenceable())
+        {
+          return *this ? base_pointer::get()->write(os) : os << magenta("()");
+        }
+        else
+        {
+          return base_pointer::write(os);
+        }
+      }
+
+      friend auto operator <<(std::ostream & os, gc_pointer const& datum) -> std::ostream &
+      {
+        return datum.write(os);
+      }
+
+      inline auto begin()
+      {
+        return *this ? base_pointer::get()->begin() : typename Top::iterator();
+      }
+
+      inline auto begin() const
+      {
+        return *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
+      }
+
+      inline auto cbegin() const
+      {
+        return *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
+      }
+
+      inline auto end()
+      {
+        return *this ? base_pointer::get()->end() : typename Top::iterator();
+      }
+
+      inline auto end() const
+      {
+        return *this ? base_pointer::get()->cend() : typename Top::const_iterator();
+      }
+
+      inline auto cend() const
+      {
+        return *this ? base_pointer::get()->cend() : typename Top::const_iterator();
+      }
+    };
+
     /*
        0x0000'0000'0000'0000 ~ 0x7FFF'FFFF'FFFF'FFFF
     */
diff --git a/include/meevax/memory/gc_pointer.hpp b/include/meevax/memory/gc_pointer.hpp
deleted file mode 100644
index 05403cc2d..000000000
--- a/include/meevax/memory/gc_pointer.hpp
+++ /dev/null
@@ -1,254 +0,0 @@
-/*
-   Copyright 2018-2023 Tatsuya Yamasaki.
-
-   Licensed under the Apache License, Version 2.0 (the "License");
-   you may not use this file except in compliance with the License.
-   You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-   Unless required by applicable law or agreed to in writing, software
-   distributed under the License is distributed on an "AS IS" BASIS,
-   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-   See the License for the specific language governing permissions and
-   limitations under the License.
-*/
-
-#ifndef INCLUDED_MEEVAX_MEMORY_GC_POINTER_HPP
-#define INCLUDED_MEEVAX_MEMORY_GC_POINTER_HPP
-
-#include <meevax/iostream/lexical_cast.hpp>
-#include <meevax/memory/collector.hpp>
-#include <meevax/memory/nan_boxing_pointer.hpp>
-#include <meevax/type_traits/requires.hpp>
-#include <meevax/utility/demangle.hpp>
-
-namespace meevax
-{
-inline namespace memory
-{
-  template <typename Top, typename... Ts>
-  struct gc_pointer : public nan_boxing_pointer<Top, Ts...>
-                    , private collector<Top, Ts...>::mutator
-  {
-    using base_pointer = nan_boxing_pointer<Top, Ts...>;
-
-    gc_pointer(gc_pointer const& gcp)
-      : base_pointer { gcp }
-      , collector<Top, Ts...>::mutator { gcp.object }
-    {}
-
-    gc_pointer(base_pointer const& p)
-      : base_pointer { p }
-      , collector<Top, Ts...>::mutator { base_pointer::get() }
-    {}
-
-    gc_pointer(std::nullptr_t = nullptr)
-    {}
-
-    gc_pointer(Top * top) // TODO Top const*
-      : base_pointer { top }
-      , collector<Top, Ts...>::mutator { base_pointer::get() }
-    {}
-
-    template <typename T, typename = std::enable_if_t<(std::is_same_v<T, Ts> or ... or std::is_same_v<T, double>)>>
-    gc_pointer(T const& datum)
-      : base_pointer { datum }
-    {
-      assert(base_pointer::get() == nullptr);
-    }
-
-    auto operator =(gc_pointer const& gcp) -> auto &
-    {
-      reset(gcp);
-      return *this;
-    }
-
-    auto operator =(base_pointer const& p) -> auto &
-    {
-      reset(p);
-      return *this;
-    }
-
-    auto operator =(std::nullptr_t) -> auto &
-    {
-      reset();
-      return *this;
-    }
-
-    auto reset(gc_pointer const& gcp) -> void
-    {
-      base_pointer::reset(gcp);
-      collector<Top, Ts...>::mutator::reset(gcp.object);
-    }
-
-    auto reset(base_pointer const& p) -> void
-    {
-      base_pointer::reset(p);
-      collector<Top, Ts...>::mutator::reset(base_pointer::get());
-    }
-
-    auto reset(std::nullptr_t = nullptr) -> void
-    {
-      base_pointer::reset();
-      collector<Top, Ts...>::mutator::reset();
-    }
-
-    template <typename Bound, typename Allocator, typename... Us>
-    static auto make(Us&&... xs) -> gc_pointer
-    {
-      if constexpr (std::is_class_v<Bound>)
-      {
-        return collector<Top, Ts...>::template make<
-                 typename collector<Top, Ts...>::template binder<
-                   Bound, std::allocator_traits<Allocator>>>(
-                     std::forward<decltype(xs)>(xs)...
-                     );
-      }
-      else
-      {
-        return { std::forward<decltype(xs)>(xs)... };
-      }
-    }
-
-    template <typename U>
-    inline auto as() const -> decltype(auto)
-    {
-      if constexpr (std::is_same_v<std::decay_t<U>, Top>)
-      {
-        return base_pointer::operator *();
-      }
-      else if constexpr (std::is_class_v<std::decay_t<U>>)
-      {
-        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
-        {
-          return *data;
-        }
-        else
-        {
-          throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
-        }
-      }
-      else
-      {
-        return base_pointer::template as<U>();
-      }
-    }
-
-    template <typename U>
-    inline auto as() -> decltype(auto)
-    {
-      if constexpr (std::is_same_v<std::decay_t<U>, Top>)
-      {
-        return base_pointer::operator *();
-      }
-      else if constexpr (std::is_class_v<std::decay_t<U>>)
-      {
-        if (auto data = dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()); data)
-        {
-          return *data;
-        }
-        else
-        {
-          throw std::runtime_error(lexical_cast<std::string>("no viable conversion from ", demangle(type()), " to ", demangle(typeid(U))));
-        }
-      }
-      else
-      {
-        return base_pointer::template as<U>();
-      }
-    }
-
-    template <typename U>
-    inline auto as_const() const -> decltype(auto)
-    {
-      return as<std::add_const_t<U>>();
-    }
-
-    inline auto compare(gc_pointer const& rhs) const -> bool
-    {
-      if (base_pointer::dereferenceable())
-      {
-        return *this ? base_pointer::get()->compare(rhs.get()) : rhs.is<std::nullptr_t>();
-      }
-      else
-      {
-        return base_pointer::compare(rhs);
-      }
-    }
-
-    template <typename U>
-    inline auto is() const
-    {
-      return type() == typeid(std::decay_t<U>);
-    }
-
-    template <typename U, REQUIRES(std::is_class<U>)>
-    inline auto is_also() const
-    {
-      return dynamic_cast<std::add_pointer_t<U>>(base_pointer::get()) != nullptr;
-    }
-
-    inline auto type() const -> std::type_info const&
-    {
-      if (base_pointer::dereferenceable())
-      {
-        return *this ? base_pointer::get()->type() : typeid(std::nullptr_t);
-      }
-      else
-      {
-        return base_pointer::type();
-      }
-    }
-
-    inline auto write(std::ostream & os) const -> std::ostream &
-    {
-      if (base_pointer::dereferenceable())
-      {
-        return *this ? base_pointer::get()->write(os) : os << magenta("()");
-      }
-      else
-      {
-        return base_pointer::write(os);
-      }
-    }
-
-    friend auto operator <<(std::ostream & os, gc_pointer const& datum) -> std::ostream &
-    {
-      return datum.write(os);
-    }
-
-    inline auto begin()
-    {
-      return *this ? base_pointer::get()->begin() : typename Top::iterator();
-    }
-
-    inline auto begin() const
-    {
-      return *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
-    }
-
-    inline auto cbegin() const
-    {
-      return *this ? base_pointer::get()->cbegin() : typename Top::const_iterator();
-    }
-
-    inline auto end()
-    {
-      return *this ? base_pointer::get()->end() : typename Top::iterator();
-    }
-
-    inline auto end() const
-    {
-      return *this ? base_pointer::get()->cend() : typename Top::const_iterator();
-    }
-
-    inline auto cend() const
-    {
-      return *this ? base_pointer::get()->cend() : typename Top::const_iterator();
-    }
-  };
-} // namespace memory
-} // namespace meevax
-
-#endif // INCLUDED_MEEVAX_MEMORY_GC_POINTER_HPP

From 78398026803fd3443248cc492173315a91d8638e Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 23 Mar 2024 03:32:53 +0900
Subject: [PATCH 35/40] Unify `gc_pointer` and `mutator`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                           |   6 +-
 VERSION                             |   2 +-
 include/meevax/kernel/pair.hpp      |  10 +-
 include/meevax/memory/collector.hpp | 143 ++++++++++------------------
 4 files changed, 57 insertions(+), 104 deletions(-)

diff --git a/README.md b/README.md
index 50cc40c32..c92d76b50 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.153_amd64.deb
+sudo apt install build/meevax_0.5.154_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.153.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.154.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.153_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.154_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 04b5f01f1..b0e2452a4 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.153
+0.5.154
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 8dca367df..6cb5f0e8c 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -32,7 +32,7 @@ inline namespace kernel
 
   using default_collector = collector<pair, bool, int, float, character, instruction>;
 
-  using object = default_collector::gc_pointer;
+  using object = default_collector::mutator;
 
   using let = object;
 
@@ -41,16 +41,16 @@ inline namespace kernel
   template <typename T, typename Allocator, typename... Ts>
   auto make(Ts&&... xs) -> decltype(auto)
   {
-    return object::make<T, Allocator>(std::forward<decltype(xs)>(xs)...);
+    return default_collector::make<T, Allocator>(std::forward<decltype(xs)>(xs)...);
   }
 
   template <typename T, typename... Ts>
   auto make(Ts&&... xs) -> decltype(auto)
   {
     if constexpr (std::is_same_v<T, pair>) {
-      return object::make<T, simple_allocator<void>>(std::forward<decltype(xs)>(xs)...);
+      return default_collector::make<T, simple_allocator<void>>(std::forward<decltype(xs)>(xs)...);
     } else {
-      return object::make<T, default_allocator<void>>(std::forward<decltype(xs)>(xs)...);
+      return default_collector::make<T, default_allocator<void>>(std::forward<decltype(xs)>(xs)...);
     }
   }
 
@@ -58,7 +58,7 @@ inline namespace kernel
             typename Allocator = default_allocator<void>>
   auto make(T&& x) -> decltype(auto)
   {
-    return object::make<std::decay_t<T>, Allocator>(std::forward<decltype(x)>(x));
+    return default_collector::make<std::decay_t<T>, Allocator>(std::forward<decltype(x)>(x));
   }
 
   template <template <typename...> typename Traits,
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 09649eec7..e335aff64 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -165,81 +165,46 @@ inline namespace memory
       }
     };
 
-    class mutator
+    struct mutator : public nan_boxing_pointer<Top, Ts...>
     {
-      friend class collector;
-
-    protected:
-      top const* object = nullptr;
+      using base_pointer = nan_boxing_pointer<Top, Ts...>;
 
-      mutator() = default;
+      mutator(std::nullptr_t = nullptr)
+      {}
 
-      explicit mutator(top const* object) noexcept
-        : object { object }
+      mutator(mutator const& other)
+        : base_pointer { other }
       {
-        if (object)
+        if (*this)
         {
           mutators.insert(this);
         }
       }
 
-      ~mutator() noexcept
-      {
-        mutators.erase(this);
-      }
-
-      auto reset(top const* after = nullptr) noexcept -> void
+      mutator(Top * top)
+        : base_pointer { top }
       {
-        if (object = after; after)
+        if (top)
         {
           mutators.insert(this);
         }
-        else
-        {
-          mutators.erase(this);
-        }
       }
-    };
-
-    struct gc_pointer : public nan_boxing_pointer<Top, Ts...>
-                      , private collector<Top, Ts...>::mutator
-    {
-      using base_pointer = nan_boxing_pointer<Top, Ts...>;
-
-      gc_pointer(gc_pointer const& gcp)
-        : base_pointer { gcp }
-        , collector<Top, Ts...>::mutator { gcp.object }
-      {}
-
-      gc_pointer(base_pointer const& p)
-        : base_pointer { p }
-        , collector<Top, Ts...>::mutator { base_pointer::get() }
-      {}
-
-      gc_pointer(std::nullptr_t = nullptr)
-      {}
-
-      gc_pointer(Top * top) // TODO Top const*
-        : base_pointer { top }
-        , collector<Top, Ts...>::mutator { base_pointer::get() }
-      {}
 
       template <typename T, typename = std::enable_if_t<(std::is_same_v<T, Ts> or ... or std::is_same_v<T, double>)>>
-      gc_pointer(T const& datum)
+      mutator(T const& datum)
         : base_pointer { datum }
       {
         assert(base_pointer::get() == nullptr);
       }
 
-      auto operator =(gc_pointer const& gcp) -> auto &
+      ~mutator()
       {
-        reset(gcp);
-        return *this;
+        mutators.erase(this);
       }
 
-      auto operator =(base_pointer const& p) -> auto &
+      auto operator =(mutator const& other) -> auto &
       {
-        reset(p);
+        reset(other);
         return *this;
       }
 
@@ -249,41 +214,24 @@ inline namespace memory
         return *this;
       }
 
-      auto reset(gc_pointer const& gcp) -> void
-      {
-        base_pointer::reset(gcp);
-        collector<Top, Ts...>::mutator::reset(gcp.object);
-      }
-
-      auto reset(base_pointer const& p) -> void
-      {
-        base_pointer::reset(p);
-        collector<Top, Ts...>::mutator::reset(base_pointer::get());
-      }
-
-      auto reset(std::nullptr_t = nullptr) -> void
-      {
-        base_pointer::reset();
-        collector<Top, Ts...>::mutator::reset();
-      }
-
-      template <typename Bound, typename Allocator, typename... Us>
-      static auto make(Us&&... xs) -> gc_pointer
+      auto reset(mutator const& other) -> void
       {
-        if constexpr (std::is_class_v<Bound>)
+        if (base_pointer::reset(other); other)
         {
-          return collector<Top, Ts...>::template make<
-                   typename collector<Top, Ts...>::template binder<
-                     Bound, std::allocator_traits<Allocator>>>(
-                       std::forward<decltype(xs)>(xs)...
-                       );
+          mutators.insert(this);
         }
         else
         {
-          return { std::forward<decltype(xs)>(xs)... };
+          mutators.erase(this);
         }
       }
 
+      auto reset(std::nullptr_t = nullptr) -> void
+      {
+        base_pointer::reset();
+        mutators.erase(this);
+      }
+
       template <typename U>
       inline auto as() const -> decltype(auto)
       {
@@ -338,7 +286,7 @@ inline namespace memory
         return as<std::add_const_t<U>>();
       }
 
-      inline auto compare(gc_pointer const& rhs) const -> bool
+      inline auto compare(mutator const& rhs) const -> bool
       {
         if (base_pointer::dereferenceable())
         {
@@ -386,7 +334,7 @@ inline namespace memory
         }
       }
 
-      friend auto operator <<(std::ostream & os, gc_pointer const& datum) -> std::ostream &
+      friend auto operator <<(std::ostream & os, mutator const& datum) -> std::ostream &
       {
         return datum.write(os);
       }
@@ -452,25 +400,30 @@ inline namespace memory
 
     auto operator =(collector const&) -> collector & = delete;
 
-    template <typename T, typename... Us>
-    static auto make(Us&&... xs)
+    template <typename T, typename Allocator, typename... Us>
+    static auto make(Us&&... xs) -> mutator
     {
-      static_assert(std::is_base_of_v<top, T>);
-
-      if (allocation += sizeof(T); threshold < allocation)
+      if constexpr (std::is_class_v<T>)
       {
-        collect();
-      }
+        if (allocation += sizeof(T); threshold < allocation)
+        {
+          collect();
+        }
 
-      if (auto data = new T(std::forward<decltype(xs)>(xs)...); data)
-      {
-        objects.insert(data);
+        if (auto data = new binder<T, std::allocator_traits<Allocator>>(std::forward<decltype(xs)>(xs)...); data)
+        {
+          objects.insert(data);
 
-        return data;
+          return data;
+        }
+        else
+        {
+          throw std::bad_alloc();
+        }
       }
       else
       {
-        throw std::bad_alloc();
+        return { std::forward<decltype(xs)>(xs)... };
       }
     }
 
@@ -563,11 +516,11 @@ inline namespace memory
       for (auto&& mutator : mutators)
       {
         assert(mutator);
-        assert(mutator->object);
+        assert(mutator->get());
 
-        if (not marked_objects.contains(mutator->object) and is_root_object(mutator))
+        if (not marked_objects.contains(mutator->get()) and is_root_object(mutator))
         {
-          mark(mutator->object, marked_objects);
+          mark(mutator->get(), marked_objects);
         }
       }
 
@@ -589,7 +542,7 @@ inline namespace memory
 
         for (; lower != upper; ++lower)
         {
-          mark((*lower)->object, marked_objects);
+          mark((*lower)->get(), marked_objects);
         }
       }
     }

From b350a64a8e0ea91c0c6bb81eda0dcc730e9f680e Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 23 Mar 2024 16:09:37 +0900
Subject: [PATCH 36/40] Add new class `collector<>::mutators_view`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                           |  6 ++--
 VERSION                             |  2 +-
 include/meevax/kernel/pair.hpp      |  9 ++----
 include/meevax/memory/collector.hpp | 47 +++++++++++++++++++----------
 4 files changed, 37 insertions(+), 27 deletions(-)

diff --git a/README.md b/README.md
index c92d76b50..045c3763d 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.154_amd64.deb
+sudo apt install build/meevax_0.5.155_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.154.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.155.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.154_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.155_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index b0e2452a4..f054896b6 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.154
+0.5.155
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 6cb5f0e8c..4c1918d7d 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -160,14 +160,9 @@ inline namespace kernel
 
     auto write(std::ostream &) const -> std::ostream & override;
 
-    auto lower() const noexcept -> std::uintptr_t override
+    auto view() const noexcept -> memory::view override
     {
-      return reinterpret_cast<std::uintptr_t>(this);
-    }
-
-    auto upper() const noexcept -> std::uintptr_t override
-    {
-      return reinterpret_cast<std::uintptr_t>(this) + sizeof(*this);
+      return { this, sizeof(*this) };
     }
 
     auto begin() noexcept
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index e335aff64..350e1761b 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -43,6 +43,8 @@ inline namespace memory
   template <typename... Ts>
   using default_allocator = std::allocator<Ts...>;
 
+  using view = std::pair<void const*, std::size_t>; // TODO Adapt to C++20's std::range concept
+
   /*
      This mark-and-sweep garbage collector is based on the implementation of
      gc_ptr written by William E. Kempf and posted to CodeProject.
@@ -64,13 +66,12 @@ inline namespace memory
 
       virtual auto write(std::ostream &) const -> std::ostream & = 0;
 
-      virtual auto lower() const noexcept -> std::uintptr_t = 0;
-
-      virtual auto upper() const noexcept -> std::uintptr_t = 0;
+      virtual auto view() const noexcept -> memory::view = 0;
 
       auto contains(void const* const data) const noexcept
       {
-        return reinterpret_cast<void const*>(lower()) <= data and data < reinterpret_cast<void const*>(upper());
+        auto [address, size] = view();
+        return address <= data and data < static_cast<std::byte const*>(address) + size;
       }
     };
 
@@ -143,14 +144,9 @@ inline namespace memory
         }
       }
 
-      auto lower() const noexcept -> std::uintptr_t override
-      {
-        return reinterpret_cast<std::uintptr_t>(this);
-      }
-
-      auto upper() const noexcept -> std::uintptr_t override
+      auto view() const noexcept -> memory::view override
       {
-        return reinterpret_cast<std::uintptr_t>(this) + sizeof(*this);
+        return { this, sizeof(*this) };
       }
 
       auto operator new(std::size_t) -> void *
@@ -387,6 +383,28 @@ inline namespace memory
 
     static inline std::unordered_map<std::string, std::unique_ptr<void, void (*)(void * const)>> dynamic_linked_libraries {};
 
+    struct mutators_view
+    {
+      std::uintptr_t address;
+
+      std::size_t size;
+
+      constexpr mutators_view(view const& v)
+        : address { reinterpret_cast<std::uintptr_t>(v.first) }
+        , size    { v.second }
+      {}
+
+      auto begin() const noexcept
+      {
+        return mutators.lower_bound(reinterpret_cast<mutator const*>(address));
+      }
+
+      auto end() const noexcept
+      {
+        return mutators.lower_bound(reinterpret_cast<mutator const*>(address + size));
+      }
+    };
+
   public:
     collector() = delete;
 
@@ -537,12 +555,9 @@ inline namespace memory
       {
         marked_objects.insert(object);
 
-        auto lower = mutators.lower_bound(reinterpret_cast<mutator const*>(object->lower()));
-        auto upper = mutators.lower_bound(reinterpret_cast<mutator const*>(object->upper()));
-
-        for (; lower != upper; ++lower)
+        for (auto each : mutators_view(object->view()))
         {
-          mark((*lower)->get(), marked_objects);
+          mark(each->get(), marked_objects);
         }
       }
     }

From a9ea5325cf19e0f325a93004b2051c02ce4bec91 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sat, 23 Mar 2024 17:03:02 +0900
Subject: [PATCH 37/40] Rename class template `simple_allocator` to `allocator`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                     |  6 ++---
 VERSION                                       |  2 +-
 include/meevax/kernel/dynamic_environment.hpp |  4 ++--
 include/meevax/kernel/pair.hpp                |  9 ++++----
 .../{simple_allocator.hpp => allocator.hpp}   | 22 +++++++++----------
 include/meevax/memory/collector.hpp           | 10 ++++-----
 test/allocator.cpp                            | 16 +++++++-------
 7 files changed, 34 insertions(+), 35 deletions(-)
 rename include/meevax/memory/{simple_allocator.hpp => allocator.hpp} (81%)

diff --git a/README.md b/README.md
index 045c3763d..c4c65dd94 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.155_amd64.deb
+sudo apt install build/meevax_0.5.156_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.155.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.156.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.155_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.156_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index f054896b6..d1a9ca8b2 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.155
+0.5.156
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index fc910a20f..ddef4b29c 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -205,7 +205,7 @@ inline namespace kernel
           *  where <closure> = (c' . e)
           *
           * ----------------------------------------------------------------- */
-          s = cons(make<closure, simple_allocator<void>>(cadr(c), e), s);
+          s = cons(make<closure, allocator<void>>(cadr(c), e), s);
           c = cddr(c);
           goto fetch;
 
@@ -216,7 +216,7 @@ inline namespace kernel
           *  where <continuation> = (s e c' . d)
           *
           * ----------------------------------------------------------------- */
-          s = cons(list(make<continuation, simple_allocator<void>>(s, cons(e, cons(cadr(c), d)))), s);
+          s = cons(list(make<continuation, allocator<void>>(s, cons(e, cons(cadr(c), d)))), s);
           c = cddr(c);
           goto fetch;
 
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index 4c1918d7d..b507541ef 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -20,6 +20,7 @@
 #include <meevax/functional/compose.hpp>
 #include <meevax/kernel/character.hpp>
 #include <meevax/kernel/instruction.hpp>
+#include <meevax/memory/allocator.hpp>
 #include <meevax/memory/collector.hpp>
 
 namespace meevax
@@ -48,21 +49,21 @@ inline namespace kernel
   auto make(Ts&&... xs) -> decltype(auto)
   {
     if constexpr (std::is_same_v<T, pair>) {
-      return default_collector::make<T, simple_allocator<void>>(std::forward<decltype(xs)>(xs)...);
+      return default_collector::make<T, allocator<void>>(std::forward<decltype(xs)>(xs)...);
     } else {
-      return default_collector::make<T, default_allocator<void>>(std::forward<decltype(xs)>(xs)...);
+      return default_collector::make<T, std::allocator<void>>(std::forward<decltype(xs)>(xs)...);
     }
   }
 
   template <typename T,
-            typename Allocator = default_allocator<void>>
+            typename Allocator = std::allocator<void>>
   auto make(T&& x) -> decltype(auto)
   {
     return default_collector::make<std::decay_t<T>, Allocator>(std::forward<decltype(x)>(x));
   }
 
   template <template <typename...> typename Traits,
-            typename Allocator = default_allocator<void>,
+            typename Allocator = std::allocator<void>,
             typename... Ts,
             REQUIRES(std::is_constructible<typename Traits<Ts...>::type, Ts...>)>
   auto make(Ts&&... xs) -> decltype(auto)
diff --git a/include/meevax/memory/simple_allocator.hpp b/include/meevax/memory/allocator.hpp
similarity index 81%
rename from include/meevax/memory/simple_allocator.hpp
rename to include/meevax/memory/allocator.hpp
index 6dadbdddb..ce7097798 100644
--- a/include/meevax/memory/simple_allocator.hpp
+++ b/include/meevax/memory/allocator.hpp
@@ -14,8 +14,8 @@
    limitations under the License.
 */
 
-#ifndef INCLUDED_MEEVAX_MEMORY_SIMPLE_ALLOCATOR_HPP
-#define INCLUDED_MEEVAX_MEMORY_SIMPLE_ALLOCATOR_HPP
+#ifndef INCLUDED_MEEVAX_MEMORY_ALLOCATOR_HPP
+#define INCLUDED_MEEVAX_MEMORY_ALLOCATOR_HPP
 
 #include <cstddef>
 #include <cstdint>
@@ -30,7 +30,7 @@ inline namespace memory
    Simple Segregated Storage Allocator
 */
 template <typename T, typename Capacity = std::integral_constant<std::size_t, 1024>>
-class simple_allocator
+class allocator
 {
   struct alignas(T) chunk
   {
@@ -80,25 +80,25 @@ class simple_allocator
   template <typename U>
   struct rebind
   {
-    using other = simple_allocator<U, Capacity>;
+    using other = allocator<U, Capacity>;
   };
 
-  explicit simple_allocator()
+  explicit allocator()
     : free_space { new block() }
   {}
 
-  simple_allocator(simple_allocator &&) = delete;
+  allocator(allocator &&) = delete;
 
-  simple_allocator(simple_allocator const&) = delete;
+  allocator(allocator const&) = delete;
 
-  ~simple_allocator()
+  ~allocator()
   {
     delete free_space;
   }
 
-  auto operator =(simple_allocator &&) -> simple_allocator & = delete;
+  auto operator =(allocator &&) -> allocator & = delete;
 
-  auto operator =(simple_allocator const&) -> simple_allocator & = delete;
+  auto operator =(allocator const&) -> allocator & = delete;
 
   auto allocate(size_type = 1)
   {
@@ -126,4 +126,4 @@ class simple_allocator
 } // namespace memory
 } // namespace meevax
 
-#endif // INCLUDED_MEEVAX_MEMORY_SIMPLE_ALLOCATOR_HPP
+#endif // INCLUDED_MEEVAX_MEMORY_ALLOCATOR_HPP
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 350e1761b..7eb25ece6 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -31,7 +31,6 @@
 #include <meevax/memory/integer_set.hpp>
 #include <meevax/memory/literal.hpp>
 #include <meevax/memory/nan_boxing_pointer.hpp>
-#include <meevax/memory/simple_allocator.hpp>
 #include <meevax/type_traits/is_equality_comparable.hpp>
 #include <meevax/type_traits/is_output_streamable.hpp>
 #include <meevax/utility/demangle.hpp>
@@ -40,9 +39,6 @@ namespace meevax
 {
 inline namespace memory
 {
-  template <typename... Ts>
-  using default_allocator = std::allocator<Ts...>;
-
   using view = std::pair<void const*, std::size_t>; // TODO Adapt to C++20's std::range concept
 
   /*
@@ -77,7 +73,7 @@ inline namespace memory
 
     static inline auto cleared = false;
 
-    template <typename Bound, typename AllocatorTraits = std::allocator_traits<std::allocator<void>>>
+    template <typename Bound, typename AllocatorTraits>
     struct binder : public virtual std::conditional_t<std::is_same_v<Top, Bound>, top, Top>
                   , public Bound
     {
@@ -367,6 +363,8 @@ inline namespace memory
     };
 
     /*
+       https://www.kernel.org/doc/html/latest/arch/x86/x86_64/mm.html
+
        0x0000'0000'0000'0000 ~ 0x7FFF'FFFF'FFFF'FFFF
     */
     template <typename T>
@@ -418,7 +416,7 @@ inline namespace memory
 
     auto operator =(collector const&) -> collector & = delete;
 
-    template <typename T, typename Allocator, typename... Us>
+    template <typename T, typename Allocator = std::allocator<void>, typename... Us>
     static auto make(Us&&... xs) -> mutator
     {
       if constexpr (std::is_class_v<T>)
diff --git a/test/allocator.cpp b/test/allocator.cpp
index 658b12d80..3c6cafc2c 100644
--- a/test/allocator.cpp
+++ b/test/allocator.cpp
@@ -6,7 +6,7 @@
 
 #include <meevax/chrono/duration.hpp>
 #include <meevax/kernel/pair.hpp>
-#include <meevax/memory/simple_allocator.hpp>
+#include <meevax/memory/allocator.hpp>
 #include <meevax/utility/debug.hpp>
 #include <meevax/utility/demangle.hpp>
 
@@ -62,15 +62,15 @@ struct hoge
 auto main() -> int
 {
   std::cout << measure<int, std::allocator<int>>() << std::endl;
-  std::cout << measure<int, meevax::simple_allocator<int>>() << std::endl;
+  std::cout << measure<int, meevax::allocator<int>>() << std::endl;
 
-  std::cout << measure<meevax::pair, meevax::simple_allocator<meevax::pair>>() << std::endl;
+  std::cout << measure<meevax::pair, meevax::allocator<meevax::pair>>() << std::endl;
 
-  std::cout << measure<std::array<std::uint8_t,  1>, meevax::simple_allocator<std::array<std::uint8_t,  1>>>() << std::endl;
-  std::cout << measure<std::array<std::uint8_t,  2>, meevax::simple_allocator<std::array<std::uint8_t,  2>>>() << std::endl;
-  std::cout << measure<std::array<std::uint8_t,  4>, meevax::simple_allocator<std::array<std::uint8_t,  4>>>() << std::endl;
-  std::cout << measure<std::array<std::uint8_t,  8>, meevax::simple_allocator<std::array<std::uint8_t,  8>>>() << std::endl;
-  std::cout << measure<std::array<std::uint8_t, 16>, meevax::simple_allocator<std::array<std::uint8_t, 16>>>() << std::endl;
+  std::cout << measure<std::array<std::uint8_t,  1>, meevax::allocator<std::array<std::uint8_t,  1>>>() << std::endl;
+  std::cout << measure<std::array<std::uint8_t,  2>, meevax::allocator<std::array<std::uint8_t,  2>>>() << std::endl;
+  std::cout << measure<std::array<std::uint8_t,  4>, meevax::allocator<std::array<std::uint8_t,  4>>>() << std::endl;
+  std::cout << measure<std::array<std::uint8_t,  8>, meevax::allocator<std::array<std::uint8_t,  8>>>() << std::endl;
+  std::cout << measure<std::array<std::uint8_t, 16>, meevax::allocator<std::array<std::uint8_t, 16>>>() << std::endl;
 
   return EXIT_SUCCESS;
 }

From a891ddaae006d24770f75bcbff4342bc2c484859 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Sun, 24 Mar 2024 21:15:31 +0900
Subject: [PATCH 38/40] Add a new data member `max` to `integer_set`

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 CMakeLists.txt                        |  4 ++--
 README.md                             |  6 +++---
 VERSION                               |  2 +-
 include/meevax/memory/collector.hpp   |  7 +++++--
 include/meevax/memory/integer_set.hpp | 11 ++++++++++-
 5 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index f6e4b98c4..b5503684b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -22,8 +22,8 @@ string(JOIN " " AGGRESSIVE_OPTIMIZATION_OPTIONS
 set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_CXX_FLAGS_DEBUG "-Og -gdwarf-4") # NOTE: The `-gdwarf-4` option is set due to the following issues with Clang 14 and Valgrind versions below 3.20: https://bugzilla.mozilla.org/show_bug.cgi?id=1758782
 set(CMAKE_CXX_FLAGS_MINSIZEREL "-Os -DNDEBUG")
-set(CMAKE_CXX_FLAGS_RELEASE "-O2 -DNDEBUG ${AGGRESSIVE_OPTIMIZATION_OPTIONS}")
-set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "-O2 -gdwarf-4 -DNDEBUG")
+set(CMAKE_CXX_FLAGS_RELEASE "-O3 -DNDEBUG ${AGGRESSIVE_OPTIMIZATION_OPTIONS}")
+set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELEASE} -gdwarf-4")
 set(CMAKE_CXX_FLAGS "-Wall -Wextra -Wpedantic -pipe")
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
diff --git a/README.md b/README.md
index c4c65dd94..56b6fa626 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.156_amd64.deb
+sudo apt install build/meevax_0.5.157_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.156.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.157.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.156_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.157_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index d1a9ca8b2..92eb7c19e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.156
+0.5.157
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 7eb25ece6..6e718f008 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -161,7 +161,7 @@ inline namespace memory
     {
       using base_pointer = nan_boxing_pointer<Top, Ts...>;
 
-      mutator(std::nullptr_t = nullptr)
+      mutator(std::nullptr_t = nullptr) noexcept
       {}
 
       mutator(mutator const& other)
@@ -191,7 +191,10 @@ inline namespace memory
 
       ~mutator()
       {
-        mutators.erase(this);
+        if (not cleared)
+        {
+          mutators.erase(this);
+        }
       }
 
       auto operator =(mutator const& other) -> auto &
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index b26f2f816..847c52918 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -46,10 +46,14 @@ inline namespace memory
 
     subset * data[N] = {};
 
+    std::size_t max = 0;
+
     struct const_iterator : public std::iterator<std::bidirectional_iterator_tag, T>
     {
       subset const* const* data = nullptr;
 
+      std::size_t max = 0;
+
       std::size_t i = std::numeric_limits<std::size_t>::max();
 
       typename subset::const_iterator iter;
@@ -58,6 +62,7 @@ inline namespace memory
 
       explicit const_iterator(integer_set const* container, std::size_t i, std::uintptr_t j = 0) noexcept
         : data { container->data }
+        , max  { container->max }
         , i    { i }
       {
         assert(i <= N);
@@ -66,6 +71,7 @@ inline namespace memory
 
       explicit const_iterator(integer_set const* container) noexcept
         : data { container->data }
+        , max  { container->max }
         , i    { N }
       {
         decrement_unless_truthy();
@@ -82,13 +88,15 @@ inline namespace memory
           {
             return;
           }
-          else for (++i; good(); ++i)
+          else for (++i; i <= max; ++i)
           {
             if (data[i] and (iter = data[i]->lower_bound(0)).good())
             {
               return;
             }
           }
+
+          i = N;
         }
 
         iter = {};
@@ -209,6 +217,7 @@ inline namespace memory
       }
       else
       {
+        max = std::max(max, i);
         data[i] = new subset();
         data[i]->insert(j);
       }

From a3e66252e671c0282fbd39c47271090a28738f65 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Mon, 25 Mar 2024 19:59:40 +0900
Subject: [PATCH 39/40] Add new class `analysis` for development

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 CMakeLists.txt                      |   5 +-
 README.md                           |   6 +-
 VERSION                             |   2 +-
 include/meevax/kernel/procedure.hpp |   7 +-
 script/benchmark.sh                 |  14 ++--
 src/kernel/optimizer.cpp            | 106 ++++++++++++++++++++++++++++
 6 files changed, 122 insertions(+), 18 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index b5503684b..1679c8721 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -12,8 +12,7 @@ project(meevax
 
 include(GNUInstallDirs)
 
-string(JOIN " " AGGRESSIVE_OPTIMIZATION_OPTIONS
-  # "-flto" # This optimization causes a SEGV when compiling with Clang 10.
+string(JOIN " " ${PROJECT_NAME}_RELEASE_PLUS
   # "-fmerge-all-constants" # This optimization is very effective in reducing binary size, but non-standard to the C++ standard.
   # "-march=native" # This optimization causes "Illegal instruction" error (is Valgrind's bug) on CI.
   # "-mtune=native"
@@ -22,7 +21,7 @@ string(JOIN " " AGGRESSIVE_OPTIMIZATION_OPTIONS
 set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_CXX_FLAGS_DEBUG "-Og -gdwarf-4") # NOTE: The `-gdwarf-4` option is set due to the following issues with Clang 14 and Valgrind versions below 3.20: https://bugzilla.mozilla.org/show_bug.cgi?id=1758782
 set(CMAKE_CXX_FLAGS_MINSIZEREL "-Os -DNDEBUG")
-set(CMAKE_CXX_FLAGS_RELEASE "-O3 -DNDEBUG ${AGGRESSIVE_OPTIMIZATION_OPTIONS}")
+set(CMAKE_CXX_FLAGS_RELEASE "-O3 -flto -DNDEBUG ${${PROJECT_NAME}_RELEASE_PLUS}")
 set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELEASE} -gdwarf-4")
 set(CMAKE_CXX_FLAGS "-Wall -Wextra -Wpedantic -pipe")
 set(CMAKE_CXX_STANDARD 17)
diff --git a/README.md b/README.md
index 56b6fa626..5ed4e1ceb 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.157_amd64.deb
+sudo apt install build/meevax_0.5.158_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.157.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.158.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.157_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.158_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 92eb7c19e..439ed20f1 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.157
+0.5.158
diff --git a/include/meevax/kernel/procedure.hpp b/include/meevax/kernel/procedure.hpp
index ebf5bf507..d147009df 100644
--- a/include/meevax/kernel/procedure.hpp
+++ b/include/meevax/kernel/procedure.hpp
@@ -53,10 +53,9 @@ inline namespace kernel
   {
     std::enable_if_t<std::is_invocable_v<F> or std::is_invocable_v<F, object &>, F> invocable;
 
-    template <typename T, typename U>
-    explicit generic_procedure(T && x, U && y)
-      : primitive_procedure { std::forward<decltype(x)>(x) }
-      , invocable           { std::forward<decltype(y)>(y) }
+    explicit generic_procedure(std::string const& name, F invocable)
+      : primitive_procedure { name }
+      , invocable           { invocable }
     {}
 
     auto operator ()(object & xs) const -> object override
diff --git a/script/benchmark.sh b/script/benchmark.sh
index 4201d0d2c..1476d5e94 100755
--- a/script/benchmark.sh
+++ b/script/benchmark.sh
@@ -21,20 +21,20 @@ quotient()
 
 tsv()
 {
-  printf "script\tMeevax\tChibi-Scheme\tGauche\n"
+  printf "\tMeevax\tChibi-Scheme\tGauche\n"
 
-  for each in $(scripts)
+  for script in $(scripts)
   do
-    t0=$(real meevax       "$root/benchmark/$each.ss")
-    t1=$(real chibi-scheme "$root/benchmark/$each.ss")
-    t2=$(real gosh         "$root/benchmark/$each.ss")
+    t0=$(real meevax       "$root/benchmark/$script.ss")
+    t1=$(real chibi-scheme "$root/benchmark/$script.ss")
+    t2=$(real gosh         "$root/benchmark/$script.ss")
 
     printf "%s\t%s\t%s\t%s\n" \
-      "$each" \
+      "$script" \
       "$t0" \
       "$t1 (x$(quotient "$t0" "$t1"))" \
       "$t2 (x$(quotient "$t0" "$t2"))"
   done
 }
 
-tsv | column -t -s"$(printf '\t')"
+tsv | column --table --separator "$(printf '\t')"
diff --git a/src/kernel/optimizer.cpp b/src/kernel/optimizer.cpp
index 8329dd2b0..b6ef02dd3 100644
--- a/src/kernel/optimizer.cpp
+++ b/src/kernel/optimizer.cpp
@@ -21,6 +21,107 @@ namespace meevax
 {
 inline namespace kernel
 {
+  struct analysis
+  {
+    static constexpr auto n = 23;
+
+    std::size_t adjacencies[n][n] = {};
+
+    ~analysis()
+    {
+      constexpr std::size_t width = 18;
+
+      std::cerr << std::string(width, ' ');
+
+      for (auto i = 0; i < n; ++i)
+      {
+        std::cerr << std::setw(width) << std::right << static_cast<instruction>(i);
+      }
+
+      std::cerr << std::endl;
+
+      for (auto i = 0; i < n; ++i)
+      {
+        std::cerr << std::setw(width) << std::right << static_cast<instruction>(i);
+
+        for (auto j = 0; j < n; ++j)
+        {
+          std::cerr << std::setw(width) << std::right << adjacencies[i][j];
+        }
+
+        std::cerr << std::endl;
+      }
+    }
+
+    auto adjacency(object const& i, object const& j) -> decltype(auto)
+    {
+      return adjacencies[static_cast<std::underlying_type_t<instruction>>(i.as<instruction>())]
+                        [static_cast<std::underlying_type_t<instruction>>(j.as<instruction>())];
+    }
+  };
+
+  auto analyze(object const& c) -> void
+  {
+    assert(c.is<pair>());
+
+    assert(car(c).is<instruction>());
+
+    static auto a = analysis();
+
+    switch (car(c).as<instruction>())
+    {
+    case instruction::join:
+    case instruction::tail_call:
+    case instruction::tail_letrec:
+    case instruction::return_:
+    case instruction::stop:
+      assert(cdr(c).is<null>());
+      break;
+
+    case instruction::call:
+    case instruction::cons:
+    case instruction::drop:
+    case instruction::dummy:
+    case instruction::letrec:
+      analyze(cdr(c));
+      a.adjacency(car(c), cadr(c))++;
+      break;
+
+    case instruction::current:
+    case instruction::install:
+    case instruction::load_absolute:
+    case instruction::load_constant:
+    case instruction::load_relative:
+    case instruction::load_variadic:
+    case instruction::store_absolute:
+    case instruction::store_relative:
+    case instruction::store_variadic:
+      analyze(cddr(c));
+      a.adjacency(car(c), caddr(c))++;
+      break;
+
+    case instruction::load_closure:
+    case instruction::load_continuation:
+      analyze(cadr(c));
+      analyze(cddr(c));
+      a.adjacency(car(c), caddr(c))++;
+      break;
+
+    case instruction::select:
+      analyze(cadr(c));
+      analyze(caddr(c));
+      analyze(cdddr(c));
+      a.adjacency(car(c), cadddr(c))++;
+      break;
+
+    case instruction::tail_select:
+      assert(cdddr(c).is<null>());
+      analyze(cadr(c));
+      analyze(caddr(c));
+      break;
+    }
+  }
+
   auto merge_constants(object & c) -> void
   {
     assert(c.is<pair>());
@@ -106,6 +207,11 @@ inline namespace kernel
   {
     merge_constants(code);
 
+    if constexpr (false)
+    {
+      analyze(code);
+    }
+
     return code;
   }
 } // namespace kernel

From fe177f4f811f1ca2ec81604509f42877edcb4a55 Mon Sep 17 00:00:00 2001
From: yamacir-kit <httperror@404-notfound.jp>
Date: Wed, 27 Mar 2024 00:20:53 +0900
Subject: [PATCH 40/40] Update copyright notice

Signed-off-by: yamacir-kit <httperror@404-notfound.jp>
---
 README.md                                                | 6 +++---
 VERSION                                                  | 2 +-
 basis/include/meevax/basis.hpp                           | 2 +-
 configure/basis.cpp                                      | 2 +-
 configure/version.cpp                                    | 2 +-
 include/meevax/bit/bit_cast.hpp                          | 2 +-
 include/meevax/bit/log2.hpp                              | 2 +-
 include/meevax/bitset/simple_bitset.hpp                  | 2 +-
 include/meevax/chrono/duration.hpp                       | 2 +-
 include/meevax/functional/combinator.hpp                 | 2 +-
 include/meevax/functional/compose.hpp                    | 2 +-
 include/meevax/functional/curry.hpp                      | 2 +-
 include/meevax/iostream/escape_sequence.hpp              | 2 +-
 include/meevax/iostream/is_console.hpp                   | 2 +-
 include/meevax/iostream/lexical_cast.hpp                 | 2 +-
 include/meevax/iterator/index_iterator.hpp               | 2 +-
 include/meevax/kernel/binary_input_file_port.hpp         | 2 +-
 include/meevax/kernel/binary_input_port.hpp              | 2 +-
 include/meevax/kernel/binary_output_file_port.hpp        | 2 +-
 include/meevax/kernel/binary_output_port.hpp             | 2 +-
 include/meevax/kernel/binary_port.hpp                    | 2 +-
 include/meevax/kernel/boolean.hpp                        | 2 +-
 include/meevax/kernel/boot.hpp                           | 2 +-
 include/meevax/kernel/box.hpp                            | 2 +-
 include/meevax/kernel/character.hpp                      | 2 +-
 include/meevax/kernel/closure.hpp                        | 2 +-
 include/meevax/kernel/comparator.hpp                     | 2 +-
 include/meevax/kernel/complex.hpp                        | 2 +-
 include/meevax/kernel/configurator.hpp                   | 2 +-
 include/meevax/kernel/continuation.hpp                   | 2 +-
 include/meevax/kernel/dynamic_environment.hpp            | 2 +-
 include/meevax/kernel/environment.hpp                    | 2 +-
 include/meevax/kernel/eof.hpp                            | 2 +-
 include/meevax/kernel/error.hpp                          | 2 +-
 include/meevax/kernel/exact_integer.hpp                  | 2 +-
 include/meevax/kernel/ghost.hpp                          | 2 +-
 include/meevax/kernel/homogeneous_vector.hpp             | 2 +-
 include/meevax/kernel/identifier.hpp                     | 2 +-
 include/meevax/kernel/identity.hpp                       | 2 +-
 include/meevax/kernel/implementation_dependent.hpp       | 2 +-
 include/meevax/kernel/include.hpp                        | 2 +-
 include/meevax/kernel/input_file_port.hpp                | 2 +-
 include/meevax/kernel/input_homogeneous_vector_port.hpp  | 2 +-
 include/meevax/kernel/input_port.hpp                     | 2 +-
 include/meevax/kernel/input_string_port.hpp              | 2 +-
 include/meevax/kernel/instruction.hpp                    | 2 +-
 include/meevax/kernel/interaction_environment.hpp        | 2 +-
 include/meevax/kernel/library.hpp                        | 2 +-
 include/meevax/kernel/list.hpp                           | 2 +-
 include/meevax/kernel/number.hpp                         | 2 +-
 include/meevax/kernel/optimizer.hpp                      | 2 +-
 include/meevax/kernel/output_file_port.hpp               | 2 +-
 include/meevax/kernel/output_homogeneous_vector_port.hpp | 2 +-
 include/meevax/kernel/output_port.hpp                    | 2 +-
 include/meevax/kernel/output_string_port.hpp             | 2 +-
 include/meevax/kernel/pair.hpp                           | 2 +-
 include/meevax/kernel/port.hpp                           | 2 +-
 include/meevax/kernel/procedure.hpp                      | 2 +-
 include/meevax/kernel/ratio.hpp                          | 2 +-
 include/meevax/kernel/standard_error_port.hpp            | 2 +-
 include/meevax/kernel/standard_input_port.hpp            | 2 +-
 include/meevax/kernel/standard_output_port.hpp           | 2 +-
 include/meevax/kernel/string.hpp                         | 2 +-
 include/meevax/kernel/symbol.hpp                         | 2 +-
 include/meevax/kernel/syntactic_environment.hpp          | 2 +-
 include/meevax/kernel/textual_input_port.hpp             | 2 +-
 include/meevax/kernel/textual_output_port.hpp            | 2 +-
 include/meevax/kernel/textual_port.hpp                   | 2 +-
 include/meevax/kernel/transformer.hpp                    | 2 +-
 include/meevax/kernel/vector.hpp                         | 2 +-
 include/meevax/kernel/version.hpp                        | 2 +-
 include/meevax/map/simple_flat_map.hpp                   | 2 +-
 include/meevax/memory/allocator.hpp                      | 2 +-
 include/meevax/memory/collector.hpp                      | 2 +-
 include/meevax/memory/integer_set.hpp                    | 2 +-
 include/meevax/memory/literal.hpp                        | 2 +-
 include/meevax/memory/model.hpp                          | 2 +-
 include/meevax/memory/nan_boxing_pointer.hpp             | 2 +-
 include/meevax/memory/pointer_set.hpp                    | 2 +-
 include/meevax/memory/simple_pointer.hpp                 | 2 +-
 include/meevax/memory/tagged_pointer.hpp                 | 2 +-
 include/meevax/type_traits/integer.hpp                   | 2 +-
 include/meevax/type_traits/is_array_subscriptable.hpp    | 2 +-
 include/meevax/type_traits/is_dereferenceable.hpp        | 2 +-
 include/meevax/type_traits/is_equality_comparable.hpp    | 2 +-
 include/meevax/type_traits/is_output_streamable.hpp      | 2 +-
 include/meevax/type_traits/is_reference_wrapper.hpp      | 2 +-
 include/meevax/type_traits/requires.hpp                  | 2 +-
 include/meevax/utility/combination.hpp                   | 2 +-
 include/meevax/utility/debug.hpp                         | 2 +-
 include/meevax/utility/demangle.hpp                      | 2 +-
 include/meevax/utility/hexdump.hpp                       | 2 +-
 include/meevax/utility/unwrap_reference_wrapper.hpp      | 2 +-
 src/chrono/duration.cpp                                  | 2 +-
 src/kernel/binary_input_file_port.cpp                    | 2 +-
 src/kernel/binary_output_file_port.cpp                   | 2 +-
 src/kernel/boolean.cpp                                   | 2 +-
 src/kernel/boot.cpp                                      | 2 +-
 src/kernel/box.cpp                                       | 2 +-
 src/kernel/character.cpp                                 | 2 +-
 src/kernel/closure.cpp                                   | 2 +-
 src/kernel/comparator.cpp                                | 2 +-
 src/kernel/complex.cpp                                   | 2 +-
 src/kernel/continuation.cpp                              | 2 +-
 src/kernel/environment.cpp                               | 2 +-
 src/kernel/eof.cpp                                       | 2 +-
 src/kernel/error.cpp                                     | 2 +-
 src/kernel/exact_integer.cpp                             | 2 +-
 src/kernel/ghost.cpp                                     | 2 +-
 src/kernel/identity.cpp                                  | 2 +-
 src/kernel/implementation_dependent.cpp                  | 2 +-
 src/kernel/include.cpp                                   | 2 +-
 src/kernel/input_file_port.cpp                           | 2 +-
 src/kernel/input_string_port.cpp                         | 2 +-
 src/kernel/instruction.cpp                               | 2 +-
 src/kernel/interaction_environment.cpp                   | 2 +-
 src/kernel/library.cpp                                   | 2 +-
 src/kernel/list.cpp                                      | 2 +-
 src/kernel/number.cpp                                    | 2 +-
 src/kernel/optimizer.cpp                                 | 2 +-
 src/kernel/output_file_port.cpp                          | 2 +-
 src/kernel/output_string_port.cpp                        | 2 +-
 src/kernel/pair.cpp                                      | 2 +-
 src/kernel/procedure.cpp                                 | 2 +-
 src/kernel/ratio.cpp                                     | 2 +-
 src/kernel/standard_error_port.cpp                       | 2 +-
 src/kernel/standard_input_port.cpp                       | 2 +-
 src/kernel/standard_output_port.cpp                      | 2 +-
 src/kernel/string.cpp                                    | 2 +-
 src/kernel/symbol.cpp                                    | 2 +-
 src/kernel/textual_input_port.cpp                        | 2 +-
 src/kernel/textual_output_port.cpp                       | 2 +-
 src/kernel/transformer.cpp                               | 2 +-
 src/kernel/vector.cpp                                    | 2 +-
 src/main.cpp                                             | 2 +-
 src/memory/model.cpp                                     | 2 +-
 src/utility/demangle.cpp                                 | 2 +-
 137 files changed, 139 insertions(+), 139 deletions(-)

diff --git a/README.md b/README.md
index 5ed4e1ceb..96d355cd0 100644
--- a/README.md
+++ b/README.md
@@ -91,7 +91,7 @@ Procedures for each standard are provided by the following R7RS-style libraries:
 cmake -B build -DCMAKE_BUILD_TYPE=Release
 cd build
 make package
-sudo apt install build/meevax_0.5.158_amd64.deb
+sudo apt install build/meevax_0.5.159_amd64.deb
 ```
 
 or
@@ -123,9 +123,9 @@ sudo rm -rf /usr/local/share/meevax
 
 | Target Name | Description
 |-------------|-------------
-| `all`       | Build shared-library `libmeevax.0.5.158.so` and executable `meevax`
+| `all`       | Build shared-library `libmeevax.0.5.159.so` and executable `meevax`
 | `test`      | Test executable `meevax`
-| `package`   | Generate debian package `meevax_0.5.158_amd64.deb`
+| `package`   | Generate debian package `meevax_0.5.159_amd64.deb`
 | `install`   | Copy files into `/usr/local` directly
 
 ## Usage
diff --git a/VERSION b/VERSION
index 439ed20f1..7948d08ba 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.5.158
+0.5.159
diff --git a/basis/include/meevax/basis.hpp b/basis/include/meevax/basis.hpp
index 9fe642b3a..c983fca78 100644
--- a/basis/include/meevax/basis.hpp
+++ b/basis/include/meevax/basis.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/configure/basis.cpp b/configure/basis.cpp
index cc6bc4a33..2dc0cd7b1 100644
--- a/configure/basis.cpp
+++ b/configure/basis.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/configure/version.cpp b/configure/version.cpp
index 45847c87e..732ec34ab 100644
--- a/configure/version.cpp
+++ b/configure/version.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/bit/bit_cast.hpp b/include/meevax/bit/bit_cast.hpp
index 352214aa3..43108b9c2 100644
--- a/include/meevax/bit/bit_cast.hpp
+++ b/include/meevax/bit/bit_cast.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/bit/log2.hpp b/include/meevax/bit/log2.hpp
index a5acc705b..c6de7be60 100644
--- a/include/meevax/bit/log2.hpp
+++ b/include/meevax/bit/log2.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/bitset/simple_bitset.hpp b/include/meevax/bitset/simple_bitset.hpp
index b5f55e6aa..9ea4f7aab 100644
--- a/include/meevax/bitset/simple_bitset.hpp
+++ b/include/meevax/bitset/simple_bitset.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/chrono/duration.hpp b/include/meevax/chrono/duration.hpp
index 28e657457..4b3999961 100644
--- a/include/meevax/chrono/duration.hpp
+++ b/include/meevax/chrono/duration.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/functional/combinator.hpp b/include/meevax/functional/combinator.hpp
index 9eecbee1c..9aeec4f31 100644
--- a/include/meevax/functional/combinator.hpp
+++ b/include/meevax/functional/combinator.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/functional/compose.hpp b/include/meevax/functional/compose.hpp
index 347b792d5..ada1c2c94 100644
--- a/include/meevax/functional/compose.hpp
+++ b/include/meevax/functional/compose.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/functional/curry.hpp b/include/meevax/functional/curry.hpp
index 51387b612..b659549ca 100644
--- a/include/meevax/functional/curry.hpp
+++ b/include/meevax/functional/curry.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/iostream/escape_sequence.hpp b/include/meevax/iostream/escape_sequence.hpp
index e758263cd..0c09990a3 100644
--- a/include/meevax/iostream/escape_sequence.hpp
+++ b/include/meevax/iostream/escape_sequence.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/iostream/is_console.hpp b/include/meevax/iostream/is_console.hpp
index 55c148b66..31e1a4d18 100644
--- a/include/meevax/iostream/is_console.hpp
+++ b/include/meevax/iostream/is_console.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/iostream/lexical_cast.hpp b/include/meevax/iostream/lexical_cast.hpp
index 9539e631c..d59ada057 100644
--- a/include/meevax/iostream/lexical_cast.hpp
+++ b/include/meevax/iostream/lexical_cast.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/iterator/index_iterator.hpp b/include/meevax/iterator/index_iterator.hpp
index 06a90015a..ff367ad65 100644
--- a/include/meevax/iterator/index_iterator.hpp
+++ b/include/meevax/iterator/index_iterator.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/binary_input_file_port.hpp b/include/meevax/kernel/binary_input_file_port.hpp
index d745d6ccd..c24896966 100644
--- a/include/meevax/kernel/binary_input_file_port.hpp
+++ b/include/meevax/kernel/binary_input_file_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/binary_input_port.hpp b/include/meevax/kernel/binary_input_port.hpp
index 29838d3bc..07c1a27ef 100644
--- a/include/meevax/kernel/binary_input_port.hpp
+++ b/include/meevax/kernel/binary_input_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/binary_output_file_port.hpp b/include/meevax/kernel/binary_output_file_port.hpp
index c341a67fa..89359b3f5 100644
--- a/include/meevax/kernel/binary_output_file_port.hpp
+++ b/include/meevax/kernel/binary_output_file_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/binary_output_port.hpp b/include/meevax/kernel/binary_output_port.hpp
index 6ccd14f85..475bc4303 100644
--- a/include/meevax/kernel/binary_output_port.hpp
+++ b/include/meevax/kernel/binary_output_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/binary_port.hpp b/include/meevax/kernel/binary_port.hpp
index f0f23fe15..9665a205a 100644
--- a/include/meevax/kernel/binary_port.hpp
+++ b/include/meevax/kernel/binary_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/boolean.hpp b/include/meevax/kernel/boolean.hpp
index 8a0065fc6..74db373a7 100644
--- a/include/meevax/kernel/boolean.hpp
+++ b/include/meevax/kernel/boolean.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/boot.hpp b/include/meevax/kernel/boot.hpp
index 52930e1ad..d7eaa7781 100644
--- a/include/meevax/kernel/boot.hpp
+++ b/include/meevax/kernel/boot.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/box.hpp b/include/meevax/kernel/box.hpp
index 9ca99cc62..92bcdc4fc 100644
--- a/include/meevax/kernel/box.hpp
+++ b/include/meevax/kernel/box.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/character.hpp b/include/meevax/kernel/character.hpp
index b6a115ff5..59533cc1a 100644
--- a/include/meevax/kernel/character.hpp
+++ b/include/meevax/kernel/character.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/closure.hpp b/include/meevax/kernel/closure.hpp
index 7e0c2ffa7..1fc2bec9d 100644
--- a/include/meevax/kernel/closure.hpp
+++ b/include/meevax/kernel/closure.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/comparator.hpp b/include/meevax/kernel/comparator.hpp
index 495fd1d64..314696b73 100644
--- a/include/meevax/kernel/comparator.hpp
+++ b/include/meevax/kernel/comparator.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/complex.hpp b/include/meevax/kernel/complex.hpp
index df05495bb..e3417550f 100644
--- a/include/meevax/kernel/complex.hpp
+++ b/include/meevax/kernel/complex.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/configurator.hpp b/include/meevax/kernel/configurator.hpp
index 07b1a477a..4255e5d1d 100644
--- a/include/meevax/kernel/configurator.hpp
+++ b/include/meevax/kernel/configurator.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/continuation.hpp b/include/meevax/kernel/continuation.hpp
index bfedb7fb5..2a5762c10 100644
--- a/include/meevax/kernel/continuation.hpp
+++ b/include/meevax/kernel/continuation.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/dynamic_environment.hpp b/include/meevax/kernel/dynamic_environment.hpp
index ddef4b29c..6752f26e4 100644
--- a/include/meevax/kernel/dynamic_environment.hpp
+++ b/include/meevax/kernel/dynamic_environment.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/environment.hpp b/include/meevax/kernel/environment.hpp
index 5b945144f..ce348e912 100644
--- a/include/meevax/kernel/environment.hpp
+++ b/include/meevax/kernel/environment.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/eof.hpp b/include/meevax/kernel/eof.hpp
index 1be6f5fc1..76e17f29f 100644
--- a/include/meevax/kernel/eof.hpp
+++ b/include/meevax/kernel/eof.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/error.hpp b/include/meevax/kernel/error.hpp
index 8f6326ea1..f441bc983 100644
--- a/include/meevax/kernel/error.hpp
+++ b/include/meevax/kernel/error.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/exact_integer.hpp b/include/meevax/kernel/exact_integer.hpp
index 2a70f15f1..3d2dff835 100644
--- a/include/meevax/kernel/exact_integer.hpp
+++ b/include/meevax/kernel/exact_integer.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/ghost.hpp b/include/meevax/kernel/ghost.hpp
index 79a467a9f..ead7c2b4f 100644
--- a/include/meevax/kernel/ghost.hpp
+++ b/include/meevax/kernel/ghost.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/homogeneous_vector.hpp b/include/meevax/kernel/homogeneous_vector.hpp
index bca80268f..5b0822600 100644
--- a/include/meevax/kernel/homogeneous_vector.hpp
+++ b/include/meevax/kernel/homogeneous_vector.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/identifier.hpp b/include/meevax/kernel/identifier.hpp
index 11bdf4ffc..de36684f2 100644
--- a/include/meevax/kernel/identifier.hpp
+++ b/include/meevax/kernel/identifier.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/identity.hpp b/include/meevax/kernel/identity.hpp
index 68ff48d0a..fcb32d145 100644
--- a/include/meevax/kernel/identity.hpp
+++ b/include/meevax/kernel/identity.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/implementation_dependent.hpp b/include/meevax/kernel/implementation_dependent.hpp
index 81c8a5762..1d65f4ee0 100644
--- a/include/meevax/kernel/implementation_dependent.hpp
+++ b/include/meevax/kernel/implementation_dependent.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/include.hpp b/include/meevax/kernel/include.hpp
index 6b6c1ef50..e0383d66c 100644
--- a/include/meevax/kernel/include.hpp
+++ b/include/meevax/kernel/include.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/input_file_port.hpp b/include/meevax/kernel/input_file_port.hpp
index 50c88e8f4..d2685b042 100644
--- a/include/meevax/kernel/input_file_port.hpp
+++ b/include/meevax/kernel/input_file_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/input_homogeneous_vector_port.hpp b/include/meevax/kernel/input_homogeneous_vector_port.hpp
index 9903d1922..d278932f9 100644
--- a/include/meevax/kernel/input_homogeneous_vector_port.hpp
+++ b/include/meevax/kernel/input_homogeneous_vector_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/input_port.hpp b/include/meevax/kernel/input_port.hpp
index b7640eb55..e6ffd6ea7 100644
--- a/include/meevax/kernel/input_port.hpp
+++ b/include/meevax/kernel/input_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/input_string_port.hpp b/include/meevax/kernel/input_string_port.hpp
index b3decfa02..2f1efb565 100644
--- a/include/meevax/kernel/input_string_port.hpp
+++ b/include/meevax/kernel/input_string_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/instruction.hpp b/include/meevax/kernel/instruction.hpp
index 44526f689..6847c5df4 100644
--- a/include/meevax/kernel/instruction.hpp
+++ b/include/meevax/kernel/instruction.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/interaction_environment.hpp b/include/meevax/kernel/interaction_environment.hpp
index 3fc3bcdb8..4fc778b59 100644
--- a/include/meevax/kernel/interaction_environment.hpp
+++ b/include/meevax/kernel/interaction_environment.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/library.hpp b/include/meevax/kernel/library.hpp
index 7d4fd291a..7d4c0c1fc 100644
--- a/include/meevax/kernel/library.hpp
+++ b/include/meevax/kernel/library.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/list.hpp b/include/meevax/kernel/list.hpp
index afea0468a..8b3138b05 100644
--- a/include/meevax/kernel/list.hpp
+++ b/include/meevax/kernel/list.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/number.hpp b/include/meevax/kernel/number.hpp
index 5fce56d68..1dd0ba0d7 100644
--- a/include/meevax/kernel/number.hpp
+++ b/include/meevax/kernel/number.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/optimizer.hpp b/include/meevax/kernel/optimizer.hpp
index 0e4a8586a..56a8066d4 100644
--- a/include/meevax/kernel/optimizer.hpp
+++ b/include/meevax/kernel/optimizer.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/output_file_port.hpp b/include/meevax/kernel/output_file_port.hpp
index 21fe11adf..95000450e 100644
--- a/include/meevax/kernel/output_file_port.hpp
+++ b/include/meevax/kernel/output_file_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/output_homogeneous_vector_port.hpp b/include/meevax/kernel/output_homogeneous_vector_port.hpp
index 08883a4a2..5479c6d74 100644
--- a/include/meevax/kernel/output_homogeneous_vector_port.hpp
+++ b/include/meevax/kernel/output_homogeneous_vector_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/output_port.hpp b/include/meevax/kernel/output_port.hpp
index 60d6df414..81f94ac88 100644
--- a/include/meevax/kernel/output_port.hpp
+++ b/include/meevax/kernel/output_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/output_string_port.hpp b/include/meevax/kernel/output_string_port.hpp
index 0e7f7e607..3dc93dea8 100644
--- a/include/meevax/kernel/output_string_port.hpp
+++ b/include/meevax/kernel/output_string_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/pair.hpp b/include/meevax/kernel/pair.hpp
index b507541ef..048f4ccce 100644
--- a/include/meevax/kernel/pair.hpp
+++ b/include/meevax/kernel/pair.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/port.hpp b/include/meevax/kernel/port.hpp
index 98d7960b9..fb31a9669 100644
--- a/include/meevax/kernel/port.hpp
+++ b/include/meevax/kernel/port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/procedure.hpp b/include/meevax/kernel/procedure.hpp
index d147009df..b912d73ff 100644
--- a/include/meevax/kernel/procedure.hpp
+++ b/include/meevax/kernel/procedure.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/ratio.hpp b/include/meevax/kernel/ratio.hpp
index a4d003a20..ef55b8bdc 100644
--- a/include/meevax/kernel/ratio.hpp
+++ b/include/meevax/kernel/ratio.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/standard_error_port.hpp b/include/meevax/kernel/standard_error_port.hpp
index c37435ca1..2d39cb900 100644
--- a/include/meevax/kernel/standard_error_port.hpp
+++ b/include/meevax/kernel/standard_error_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/standard_input_port.hpp b/include/meevax/kernel/standard_input_port.hpp
index a0d4b2b6f..8816f5d60 100644
--- a/include/meevax/kernel/standard_input_port.hpp
+++ b/include/meevax/kernel/standard_input_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/standard_output_port.hpp b/include/meevax/kernel/standard_output_port.hpp
index 776cc7fa6..ce2a775be 100644
--- a/include/meevax/kernel/standard_output_port.hpp
+++ b/include/meevax/kernel/standard_output_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/string.hpp b/include/meevax/kernel/string.hpp
index a9b73d5f5..8c42cbdfb 100644
--- a/include/meevax/kernel/string.hpp
+++ b/include/meevax/kernel/string.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/symbol.hpp b/include/meevax/kernel/symbol.hpp
index 41f94626c..37176adca 100644
--- a/include/meevax/kernel/symbol.hpp
+++ b/include/meevax/kernel/symbol.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/syntactic_environment.hpp b/include/meevax/kernel/syntactic_environment.hpp
index be6703de3..d111a5752 100644
--- a/include/meevax/kernel/syntactic_environment.hpp
+++ b/include/meevax/kernel/syntactic_environment.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/textual_input_port.hpp b/include/meevax/kernel/textual_input_port.hpp
index 069453bab..41a423d36 100644
--- a/include/meevax/kernel/textual_input_port.hpp
+++ b/include/meevax/kernel/textual_input_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/textual_output_port.hpp b/include/meevax/kernel/textual_output_port.hpp
index caaaecf9c..f8b54c596 100644
--- a/include/meevax/kernel/textual_output_port.hpp
+++ b/include/meevax/kernel/textual_output_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/textual_port.hpp b/include/meevax/kernel/textual_port.hpp
index e2b18dc09..522e392e6 100644
--- a/include/meevax/kernel/textual_port.hpp
+++ b/include/meevax/kernel/textual_port.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/transformer.hpp b/include/meevax/kernel/transformer.hpp
index 47e2fea30..580f709bc 100644
--- a/include/meevax/kernel/transformer.hpp
+++ b/include/meevax/kernel/transformer.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/vector.hpp b/include/meevax/kernel/vector.hpp
index 96afe341c..f7380fe76 100644
--- a/include/meevax/kernel/vector.hpp
+++ b/include/meevax/kernel/vector.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/kernel/version.hpp b/include/meevax/kernel/version.hpp
index eeb7adf1f..59fa108c1 100644
--- a/include/meevax/kernel/version.hpp
+++ b/include/meevax/kernel/version.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/map/simple_flat_map.hpp b/include/meevax/map/simple_flat_map.hpp
index d6ecec298..b833cf7c3 100644
--- a/include/meevax/map/simple_flat_map.hpp
+++ b/include/meevax/map/simple_flat_map.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/allocator.hpp b/include/meevax/memory/allocator.hpp
index ce7097798..cee480b6b 100644
--- a/include/meevax/memory/allocator.hpp
+++ b/include/meevax/memory/allocator.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/collector.hpp b/include/meevax/memory/collector.hpp
index 6e718f008..7936d31c2 100644
--- a/include/meevax/memory/collector.hpp
+++ b/include/meevax/memory/collector.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/integer_set.hpp b/include/meevax/memory/integer_set.hpp
index 847c52918..a9c47d222 100644
--- a/include/meevax/memory/integer_set.hpp
+++ b/include/meevax/memory/integer_set.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/literal.hpp b/include/meevax/memory/literal.hpp
index 23fd26cb9..7649bc4d5 100644
--- a/include/meevax/memory/literal.hpp
+++ b/include/meevax/memory/literal.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/model.hpp b/include/meevax/memory/model.hpp
index cb4228dff..889c1e94e 100644
--- a/include/meevax/memory/model.hpp
+++ b/include/meevax/memory/model.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/nan_boxing_pointer.hpp b/include/meevax/memory/nan_boxing_pointer.hpp
index 9fad8ceba..13d19bdb0 100644
--- a/include/meevax/memory/nan_boxing_pointer.hpp
+++ b/include/meevax/memory/nan_boxing_pointer.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/pointer_set.hpp b/include/meevax/memory/pointer_set.hpp
index b0fd052de..94ce4a2fe 100644
--- a/include/meevax/memory/pointer_set.hpp
+++ b/include/meevax/memory/pointer_set.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/simple_pointer.hpp b/include/meevax/memory/simple_pointer.hpp
index 650674b0c..2fa2e0d2d 100644
--- a/include/meevax/memory/simple_pointer.hpp
+++ b/include/meevax/memory/simple_pointer.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/memory/tagged_pointer.hpp b/include/meevax/memory/tagged_pointer.hpp
index a0c43156c..a3f788e38 100644
--- a/include/meevax/memory/tagged_pointer.hpp
+++ b/include/meevax/memory/tagged_pointer.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/type_traits/integer.hpp b/include/meevax/type_traits/integer.hpp
index 5fe1ffa7d..7d24bfa7c 100644
--- a/include/meevax/type_traits/integer.hpp
+++ b/include/meevax/type_traits/integer.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/type_traits/is_array_subscriptable.hpp b/include/meevax/type_traits/is_array_subscriptable.hpp
index 93f9da9ce..0a2224da8 100644
--- a/include/meevax/type_traits/is_array_subscriptable.hpp
+++ b/include/meevax/type_traits/is_array_subscriptable.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/type_traits/is_dereferenceable.hpp b/include/meevax/type_traits/is_dereferenceable.hpp
index 393aaf7ec..1ec3e18cf 100644
--- a/include/meevax/type_traits/is_dereferenceable.hpp
+++ b/include/meevax/type_traits/is_dereferenceable.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/type_traits/is_equality_comparable.hpp b/include/meevax/type_traits/is_equality_comparable.hpp
index 4702ee7da..9af7dd53c 100644
--- a/include/meevax/type_traits/is_equality_comparable.hpp
+++ b/include/meevax/type_traits/is_equality_comparable.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/type_traits/is_output_streamable.hpp b/include/meevax/type_traits/is_output_streamable.hpp
index 74dd11891..eff1212c1 100644
--- a/include/meevax/type_traits/is_output_streamable.hpp
+++ b/include/meevax/type_traits/is_output_streamable.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/type_traits/is_reference_wrapper.hpp b/include/meevax/type_traits/is_reference_wrapper.hpp
index 14a60d6db..e49419765 100644
--- a/include/meevax/type_traits/is_reference_wrapper.hpp
+++ b/include/meevax/type_traits/is_reference_wrapper.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/type_traits/requires.hpp b/include/meevax/type_traits/requires.hpp
index 96fe8db5f..24fe77313 100644
--- a/include/meevax/type_traits/requires.hpp
+++ b/include/meevax/type_traits/requires.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/utility/combination.hpp b/include/meevax/utility/combination.hpp
index 6842933b3..7908694df 100644
--- a/include/meevax/utility/combination.hpp
+++ b/include/meevax/utility/combination.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/utility/debug.hpp b/include/meevax/utility/debug.hpp
index 5ebdf551a..2d72dcb50 100644
--- a/include/meevax/utility/debug.hpp
+++ b/include/meevax/utility/debug.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/utility/demangle.hpp b/include/meevax/utility/demangle.hpp
index e8999997d..684571fd9 100644
--- a/include/meevax/utility/demangle.hpp
+++ b/include/meevax/utility/demangle.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/utility/hexdump.hpp b/include/meevax/utility/hexdump.hpp
index da7a1227e..e625262f2 100644
--- a/include/meevax/utility/hexdump.hpp
+++ b/include/meevax/utility/hexdump.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/include/meevax/utility/unwrap_reference_wrapper.hpp b/include/meevax/utility/unwrap_reference_wrapper.hpp
index 4afd986de..9578d43e3 100644
--- a/include/meevax/utility/unwrap_reference_wrapper.hpp
+++ b/include/meevax/utility/unwrap_reference_wrapper.hpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/chrono/duration.cpp b/src/chrono/duration.cpp
index 2c1218a5b..9a8b4f052 100644
--- a/src/chrono/duration.cpp
+++ b/src/chrono/duration.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/binary_input_file_port.cpp b/src/kernel/binary_input_file_port.cpp
index 4a667af3c..4d1d89eb5 100644
--- a/src/kernel/binary_input_file_port.cpp
+++ b/src/kernel/binary_input_file_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/binary_output_file_port.cpp b/src/kernel/binary_output_file_port.cpp
index bed54bb04..2e7ff9455 100644
--- a/src/kernel/binary_output_file_port.cpp
+++ b/src/kernel/binary_output_file_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/boolean.cpp b/src/kernel/boolean.cpp
index b5493203d..474e49422 100644
--- a/src/kernel/boolean.cpp
+++ b/src/kernel/boolean.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/boot.cpp b/src/kernel/boot.cpp
index 3462a5bfc..eb96a8e16 100644
--- a/src/kernel/boot.cpp
+++ b/src/kernel/boot.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/box.cpp b/src/kernel/box.cpp
index c21aadd1c..ba7624005 100644
--- a/src/kernel/box.cpp
+++ b/src/kernel/box.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/character.cpp b/src/kernel/character.cpp
index 80afce788..107b8c49f 100644
--- a/src/kernel/character.cpp
+++ b/src/kernel/character.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/closure.cpp b/src/kernel/closure.cpp
index e7005ed8f..e5c9d58a6 100644
--- a/src/kernel/closure.cpp
+++ b/src/kernel/closure.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/comparator.cpp b/src/kernel/comparator.cpp
index 207027033..60013845b 100644
--- a/src/kernel/comparator.cpp
+++ b/src/kernel/comparator.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/complex.cpp b/src/kernel/complex.cpp
index 4e535f82d..194beb6a5 100644
--- a/src/kernel/complex.cpp
+++ b/src/kernel/complex.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/continuation.cpp b/src/kernel/continuation.cpp
index af565863d..49cdda9d2 100644
--- a/src/kernel/continuation.cpp
+++ b/src/kernel/continuation.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/environment.cpp b/src/kernel/environment.cpp
index e07b232de..44eb22d1a 100644
--- a/src/kernel/environment.cpp
+++ b/src/kernel/environment.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/eof.cpp b/src/kernel/eof.cpp
index 9e22d3812..3d94b1220 100644
--- a/src/kernel/eof.cpp
+++ b/src/kernel/eof.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/error.cpp b/src/kernel/error.cpp
index 001e8bfdc..622688962 100644
--- a/src/kernel/error.cpp
+++ b/src/kernel/error.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/exact_integer.cpp b/src/kernel/exact_integer.cpp
index 85ab62834..3c498d050 100644
--- a/src/kernel/exact_integer.cpp
+++ b/src/kernel/exact_integer.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/ghost.cpp b/src/kernel/ghost.cpp
index 397cdf159..eefff637c 100644
--- a/src/kernel/ghost.cpp
+++ b/src/kernel/ghost.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/identity.cpp b/src/kernel/identity.cpp
index 1f35a3efb..df5a8df5c 100644
--- a/src/kernel/identity.cpp
+++ b/src/kernel/identity.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/implementation_dependent.cpp b/src/kernel/implementation_dependent.cpp
index acaa6eedb..4694f6a8d 100644
--- a/src/kernel/implementation_dependent.cpp
+++ b/src/kernel/implementation_dependent.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/include.cpp b/src/kernel/include.cpp
index 5f4acd139..df0e0485b 100644
--- a/src/kernel/include.cpp
+++ b/src/kernel/include.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/input_file_port.cpp b/src/kernel/input_file_port.cpp
index 623278094..0731f42be 100644
--- a/src/kernel/input_file_port.cpp
+++ b/src/kernel/input_file_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/input_string_port.cpp b/src/kernel/input_string_port.cpp
index be509ed21..6cf0383d8 100644
--- a/src/kernel/input_string_port.cpp
+++ b/src/kernel/input_string_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/instruction.cpp b/src/kernel/instruction.cpp
index f2cb1ada6..e2e1d9dc3 100644
--- a/src/kernel/instruction.cpp
+++ b/src/kernel/instruction.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/interaction_environment.cpp b/src/kernel/interaction_environment.cpp
index 140b57610..f1ce7ed85 100644
--- a/src/kernel/interaction_environment.cpp
+++ b/src/kernel/interaction_environment.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/library.cpp b/src/kernel/library.cpp
index e5c51d818..282418bff 100644
--- a/src/kernel/library.cpp
+++ b/src/kernel/library.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/list.cpp b/src/kernel/list.cpp
index 74db185e1..4b35dd936 100644
--- a/src/kernel/list.cpp
+++ b/src/kernel/list.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/number.cpp b/src/kernel/number.cpp
index 9f2697d6a..bc7748271 100644
--- a/src/kernel/number.cpp
+++ b/src/kernel/number.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/optimizer.cpp b/src/kernel/optimizer.cpp
index b6ef02dd3..daa39b23b 100644
--- a/src/kernel/optimizer.cpp
+++ b/src/kernel/optimizer.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/output_file_port.cpp b/src/kernel/output_file_port.cpp
index 2c80334fe..04a3f10f3 100644
--- a/src/kernel/output_file_port.cpp
+++ b/src/kernel/output_file_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/output_string_port.cpp b/src/kernel/output_string_port.cpp
index ac384b930..90b0bdec7 100644
--- a/src/kernel/output_string_port.cpp
+++ b/src/kernel/output_string_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/pair.cpp b/src/kernel/pair.cpp
index 912c91732..8e0e83dfa 100644
--- a/src/kernel/pair.cpp
+++ b/src/kernel/pair.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/procedure.cpp b/src/kernel/procedure.cpp
index ad3ebe09d..1329373cf 100644
--- a/src/kernel/procedure.cpp
+++ b/src/kernel/procedure.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/ratio.cpp b/src/kernel/ratio.cpp
index bb299af19..b6405a4ab 100644
--- a/src/kernel/ratio.cpp
+++ b/src/kernel/ratio.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/standard_error_port.cpp b/src/kernel/standard_error_port.cpp
index aa868062e..c5c7eabb8 100644
--- a/src/kernel/standard_error_port.cpp
+++ b/src/kernel/standard_error_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/standard_input_port.cpp b/src/kernel/standard_input_port.cpp
index 05b267b89..3c217d5a1 100644
--- a/src/kernel/standard_input_port.cpp
+++ b/src/kernel/standard_input_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/standard_output_port.cpp b/src/kernel/standard_output_port.cpp
index 3736bb72f..dfd7cecfb 100644
--- a/src/kernel/standard_output_port.cpp
+++ b/src/kernel/standard_output_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/string.cpp b/src/kernel/string.cpp
index 8a6cc8f87..dfb03f95c 100644
--- a/src/kernel/string.cpp
+++ b/src/kernel/string.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/symbol.cpp b/src/kernel/symbol.cpp
index 0426dad78..866659fc8 100644
--- a/src/kernel/symbol.cpp
+++ b/src/kernel/symbol.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/textual_input_port.cpp b/src/kernel/textual_input_port.cpp
index c2010132a..cbe8246cd 100644
--- a/src/kernel/textual_input_port.cpp
+++ b/src/kernel/textual_input_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/textual_output_port.cpp b/src/kernel/textual_output_port.cpp
index bf2d26bbf..34cb91722 100644
--- a/src/kernel/textual_output_port.cpp
+++ b/src/kernel/textual_output_port.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/transformer.cpp b/src/kernel/transformer.cpp
index 293435886..b6e41ee79 100644
--- a/src/kernel/transformer.cpp
+++ b/src/kernel/transformer.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/kernel/vector.cpp b/src/kernel/vector.cpp
index f38946924..d8fa11faa 100644
--- a/src/kernel/vector.cpp
+++ b/src/kernel/vector.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/main.cpp b/src/main.cpp
index 2dfdc45b7..217d7a0c7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/memory/model.cpp b/src/memory/model.cpp
index 68629b50f..99b903677 100644
--- a/src/memory/model.cpp
+++ b/src/memory/model.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
diff --git a/src/utility/demangle.cpp b/src/utility/demangle.cpp
index 13bc5c846..d686c8063 100644
--- a/src/utility/demangle.cpp
+++ b/src/utility/demangle.cpp
@@ -1,5 +1,5 @@
 /*
-   Copyright 2018-2023 Tatsuya Yamasaki.
+   Copyright 2018-2024 Tatsuya Yamasaki.
 
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.