re-orgnize type definition before normalizing

lib/typing/check.ml

@@ -341,22 +341,26 @@ and check_ty_def_group defs env =
             Env.add_type_def (I.TDOpaque (name, [])) env)
       env defs
   in
-  let normalized_defs, env =
+  let defs = Util.reorg_ty_defs defs in
+  let normalized_defs, env, _ =
     List.fold_left
-      (fun (acc, env) def ->
+      (fun (acc, env, normalize_env) def ->
         match def with
         | T.TDAdt (name, ty_para_names, _) as def_ext ->
             let tid = Env.mk_tid name env in
             let def = normalize_def def_ext normalize_env in
             let[@warning "-8"] (I.TDAdt (_, _, bs)) = def in
             let env = Env.add_type_def def env in
+            let normalize_env = Env.add_type_def def normalize_env in
             let constructors = analyze_constructors tid ty_para_names bs in
             let env = Env.add_constrs constructors env in
-            (TopTypeDef def :: acc, env)
+            (TopTypeDef def :: acc, env, normalize_env)
         | _ as def_ext ->
             let def = normalize_def def_ext normalize_env in
-            (TopTypeDef def :: acc, Env.add_type_def def env))
-      ([], env) defs
+            ( TopTypeDef def :: acc,
+              Env.add_type_def def env,
+              Env.add_type_def def normalize_env ))
+      ([], env, normalize_env) defs
   in
   (normalized_defs, env)
 

lib/typing/util.ml

@@ -0,0 +1,58 @@
+module P = Syntax.Parsetree
+
+(** Two invariant must hold:
+    1. A new type definition can be correctly normalize
+    when its componnet type expressionss can be correctly
+    normalized
+    2. A type expression that indicate a type alias,
+    can be correctly normalized when the normalized alias
+    definition already added in environment.
+ *)
+let reorg_ty_defs (defs : P.ty_def list) =
+  (* analyze alias dependency *)
+  let analyze_deps defs =
+    List.fold_left
+      (fun acc def ->
+        match def with
+        | P.TDAlias (_, P.TCons (alias, _)) -> (
+            match
+              List.find_opt
+                (fun def ->
+                  match def with
+                  | P.TDAdt (name', _, _)
+                  | P.TDRecord (name', _, _)
+                  | P.TDAlias (name', _) ->
+                      alias = name')
+                defs
+            with
+            | Some def' -> (def, def') :: acc
+            | None -> acc)
+        | _ -> acc)
+      [] defs
+    |> List.rev
+  in
+  let graph = analyze_deps defs in
+  let alias_defs, no_alias_defs =
+    List.fold_left
+      (fun (ads, nads) def ->
+        match def with
+        | P.TDAlias _ -> (def :: ads, nads)
+        | _ -> (ads, def :: nads))
+      ([], []) defs
+  in
+  let no_alias_defs = List.rev no_alias_defs in
+  let visited = ref [] in
+  let rec dfs graph cluster node =
+    if not (List.memq node !visited) then (
+      let cluster = node :: cluster in
+      visited := node :: !visited;
+      match List.assoc_opt node graph with
+      | Some neighber when List.memq neighber alias_defs ->
+          dfs graph cluster neighber
+      | _ -> cluster)
+    else cluster
+  in
+  let clusters =
+    List.fold_left (fun acc def -> dfs graph [] def :: acc) [] alias_defs
+  in
+  List.flatten (List.rev clusters) @ no_alias_defs

tests/cram/test_dirs/interp.t/test_rec_ty.fun

@@ -10,7 +10,6 @@ and 'a forest =
   | EmptyForest
   | ConsForest of ('a tree * 'a forest)
 
-
 let x = Node (1, ConsForest (Leaf 1, EmptyForest))
 
 let _ =

tests/regular/typing_test.ml

@@ -1203,6 +1203,46 @@ external print_int : int ->  int = "ff_builtin_print_int"
       (TopTypeDef
         (TDAdt additive ()
           ((Add ((TTuple ((TCons (0 atom) ()) (TCons (0 atom) ())))))))))
+    |}];
+  print_typed
+    {|
+type 'a list =
+  | Nil
+  | Cons of ('a * 'a list)
+
+type env = int list
+
+and t =
+  | Closure of (string * env)
+
+let x = Closure ("x", Nil)
+
+               |};
+  [%expect {|
+    ((TopTypeDef
+       (TDAdt list ('a/0)
+         ((Nil ())
+           (Cons ((TTuple ((TQVar 'a/0) (TCons (0 list) ((TQVar 'a/0))))))))))
+      (TopTypeDef
+        (TDAdt t ()
+          ((Closure
+             ((TTuple
+                ((TCons (0 string) ()) (TCons (0 list) ((TCons (0 int) ()))))))))))
+      (TopTypeDef (TDAlias env (TCons (0 list) ((TCons (0 int) ())))))
+      (TopLet x
+        (EApp
+          (ECons Closure 0
+            (TArrow
+              (TTuple
+                ((TCons (0 string) ()) (TCons (0 list) ((TCons (0 int) ())))))
+              (TCons (0 t) ())))
+          (ETuple
+            ((EConst (CString "\"x\"") (TCons (0 string) ()))
+              (ECons Nil 0 (TCons (0 list) ((TVar (Link (TCons (0 int) ())))))))
+            (TTuple
+              ((TCons (0 string) ())
+                (TCons (0 list) ((TVar (Link (TCons (0 int) ()))))))))
+          (TVar (Link (TCons (0 t) ()))))))
     |}]
 
 let%expect_test "Error reporting test" =

tests/regular/typing_util_test.ml

@@ -0,0 +1,53 @@
+open Syntax.Parsing
+open Typing
+module U = Util
+module P = Syntax.Parsetree
+
+let print_sexp s =
+  Printf.printf "%s\n" (Sexplib.Sexp.to_string_hum ?indent:(Some 2) s)
+
+let%expect_test "Test: type def reorg" =
+  let print_ty_defs_reorgnized str =
+    Ident.refresh ();
+    let prog = parse_string_program str in
+    let[@warning "-8"] (Some defs) =
+      List.find_map
+        (fun top ->
+          match top with
+          | P.TopTypeDef defs -> Some defs
+          | _ -> None)
+        prog
+    in
+    defs |> U.reorg_ty_defs |> P.sexp_of_ty_def_group |> print_sexp
+  in
+  print_ty_defs_reorgnized {|
+type z = y
+
+and y = x
+
+and x = int
+     |};
+  [%expect
+    {|
+    ((TDAlias z (TCons y ())) (TDAlias y (TCons x ()))
+      (TDAlias x (TCons int ())))
+    |}];
+
+  print_ty_defs_reorgnized
+    {|
+type z = y
+
+and y = x
+
+and x = int
+
+and a = x
+
+and b = a 
+and c = b
+     |};
+  [%expect {|
+    ((TDAlias z (TCons y ())) (TDAlias y (TCons x ())) (TDAlias c (TCons b ()))
+      (TDAlias b (TCons a ())) (TDAlias a (TCons x ()))
+      (TDAlias x (TCons int ())))
+    |}]