diff --git a/Library/Ancillary/travisci b/Library/Ancillary/travisci
index e23cde7..562a87e 100755
--- a/Library/Ancillary/travisci
+++ b/Library/Ancillary/travisci
@@ -15,7 +15,7 @@
 
 INSTALL_PREFIX="${HOME}/.local"
 
-eval $(opam config env)
+eval $(opam config env --switch ${TRAVIS_OCAML_VERSION:?})
 autoconf
 ./configure --prefix="${INSTALL_PREFIX}"
 bmake -I "${INSTALL_PREFIX}/share/bsdowl" all
diff --git a/Makefile b/Makefile
index 2c99682..b291589 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,7 @@
 # http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.txt
 
 PACKAGE=		lemonade
-VERSION=		0.3.0
+VERSION=		0.3.1
 OFFICER=		michipili@gmail.com
 
 MODULE=			ocaml.lib:src
diff --git a/README.md b/README.md
index 665641c..60b993f 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,69 @@ monad library for OCaml.
 
 It implements the following monads:
 
-- `Lemonade_Lazy`
-- `Lemonade_List`
-- `Lemonade_Maybe`
-- `Lemonade_Success`
+- **Lemonade_Continuation** for continuation passing style programming.
+- **Lemonade_Lazy** for lazy computations.
+- **Lemonade_List** for computations yielding several possible results.
+- **Lemonade_Maybe** for computations yielding zero or one result.
+- **Lemonade_Reader** for computations explicitly depending on some environment.
+- **Lemonade_Retry** for retryable computations.
+- **Lemonade_State** for computations modifying a state.
+- **Lemonade_Success** for computations failing with context information.
+- **Lemonade_Writer** for computations writing a log book.
+
+
+## Setup guide
+
+It is easy to install **Lemonade** using **opam** and its *pinning*
+feature.  In a shell visiting the repository, say
+
+```console
+% autoconf
+% opam pin add lemonade .
+```
+
+It is also possible to install **Lemonade** manually.
+The installation procedure is based on the portable build system
+[BSD Owl Scripts][bsdowl-home] written for BSD Make.
+
+1. Verify that prerequisites are installed:
+   - BSD Make
+   - [BSD OWl][bsdowl-install]
+   - OCaml
+   - [Broken][broken-home]
+   - [Mixture][mixture-home]
+   - GNU Autoconf
+
+2. Get the source, either by cloning the repository or by exploding a
+   [distribution tarball](releases).
+
+3. Optionally run `autoconf` to produce a configuration script. This
+   is only required if the script is not already present.
+
+4. Run `./configure`, you can choose the installation prefix with
+   `--prefix`.
+
+5. Run `make build`.
+
+6. Optionally run `make test` to test your build.
+
+7. Finally run `make install`.
+
+Depending on how **BSD Make** is called on your system, you may need to
+replace `make` by `bsdmake` or `bmake` in steps 5, 6, and 7.
+The **GNU Make** program usually give up the ghost, croaking
+`*** missing separator. Stop.` when you mistakingly use it instead of
+**BSD Make**.
+
+Step 7 requires that you can `su -` if you are not already `root`.
+
+
+Michael Grünewald in Aachen, on November 12, 2015
+
+  [licence-url]:        http://www.cecill.info/licences/Licence_CeCILL-B_V1-en.html
+  [licence-en]:         COPYING
+  [licence-fr]:         COPYING-FR
+  [bsdowl-home]:        https://github.com/michipili/bsdowl
+  [bsdowl-install]:     https://github.com/michipili/bsdowl/wiki/Install
+  [broken-home]:        https://github.com/michipili/broken
+  [mixture-home]:       https://github.com/michipili/mixture
diff --git a/opam/opam b/opam/opam
index 23f2909..8c7dcab 100644
--- a/opam/opam
+++ b/opam/opam
@@ -1,6 +1,7 @@
 opam-version: "1.2"
 maintainer: "michipili@gmail.com"
 authors: "Michael Grünewald"
+version: "0.3.1"
 license: "CeCILL-B"
 homepage: "https://github.com/michipili/lemonade"
 bug-reports: "https://github.com/michipili/lemonade/issues"
@@ -25,7 +26,7 @@ remove: [
 depends: [
   "broken" {>= "0.4.2"}
   "bsdowl" {>= "3.0.0"}
-  "mixture"{>= "0.2.0"}
+  "mixture"{>= "0.2.1"}
   "ocamlfind"
 ]
 depexts: [
diff --git a/src/lemonade_Type.ml b/src/lemonade_Type.ml
index 1c79281..49cd07e 100644
--- a/src/lemonade_Type.ml
+++ b/src/lemonade_Type.ml
@@ -36,6 +36,7 @@ sig
     val ( <* ) : 'a t -> 'b t -> 'a t
     val ( >* ) : 'a t -> 'b t -> 'b t
     val ( >>= ) : 'a t -> ('a -> 'b t) -> 'b t
+    val ( >|= ) : 'a t -> ('a -> 'b) -> 'b t
     val ( >> ) : 'a t -> (unit -> 'b t) -> 'b t
     val ( >=> ) : ('a -> 'b t) -> ('b -> 'c t) -> ('a -> 'c t)
     val ( <=< ) : ('b -> 'c t) -> ('a -> 'b t) -> ('a -> 'c t)
diff --git a/src/lemonade_Type.mli b/src/lemonade_Type.mli
index f2f71e3..842c89d 100644
--- a/src/lemonade_Type.mli
+++ b/src/lemonade_Type.mli
@@ -88,6 +88,9 @@ sig
     val ( >>= ) : 'a t -> ('a -> 'b t) -> 'b t
     (** [ m >>= f] is equivalent to [bind m f]. *)
 
+    val ( >|= ) : 'a t -> ('a -> 'b) -> 'b t
+    (** A composable shorthand for [map]. *)
+
     val ( >> ) : 'a t -> (unit -> 'b t) -> 'b t
     (** [m >> f] binds [m] to [f], a context function. *)