Detect cycles in type declarations

[tiger.ml.git] / compiler / src / lib / tiger / tiger_env_type.ml

diff --git a/compiler/src/lib/tiger/tiger_env_type.ml b/compiler/src/lib/tiger/tiger_env_type.ml
index bb8cdd6..a2e719f 100644 (file)
--- a/compiler/src/lib/tiger/tiger_env_type.ml
+++ b/compiler/src/lib/tiger/tiger_env_type.ml
@@ -45,7 +45,10 @@ let new_array ty =
 
 let is_equal t1 t2 =
   match t1, t2 with
+  | Name   (s1, _)       ,  Name   (s2, _)        -> Symbol.is_equal s1 s2
   | Record {unique=u1; _},  Record {unique=u2; _} -> u1 == u2
+  | Record _             ,  Nil                   -> true
+  | Nil                  ,  Record _              -> true
   | Array  {unique=u1; _},  Array  {unique=u2; _} -> u1 == u2
   | t1                   , t2                     -> t1 =  t2
   (* The above pattern matching is "fragile" and I'm OK with it.
@@ -97,6 +100,18 @@ let if_record t ~f ~otherwise =
   | Array  _ ->
       otherwise ()
 
+let if_array t ~f ~otherwise =
+  match t with
+  | Array {ty=t; _} ->
+      f t
+  | Unit
+  | Int
+  | String
+  | Name _
+  | Nil
+  | Record _ ->
+      otherwise ()
+
 let to_string = function
   | Unit               -> "unit"
   | Nil                -> "nil"