Custom base types

[hcoop/domtool2.git] / src / tycheck.sml

diff --git a/src/tycheck.sml b/src/tycheck.sml
index fa006df..30a1d86 100644 (file)
--- a/src/tycheck.sml
+++ b/src/tycheck.sml
@@ -281,6 +281,18 @@ fun whnorm (tAll as (t, loc)) =
        TUnif (_, ref (SOME tAll)) => whnorm tAll
       | _ => tAll
 
+fun hasTyp (e, t1, t2) =
+    case whnorm t2 of
+       (TBase name, _) =>
+       (case typeRule name of
+            NONE => subTyp (t1, t2)
+          | SOME rule =>
+            if rule e then
+                ()
+            else
+                subTyp (t1, t2))
+      | _ => subTyp (t1, t2)
+
 fun checkTyp G (tAll as (t, loc)) =
     let
        val err = ErrorMsg.error (SOME loc)
@@ -316,7 +328,7 @@ fun checkExp G (eAll as (e, loc)) =
                          let
                              val t' = checkExp G e'
                          in
-                             (subTyp (t', t);
+                             (hasTyp (eAll, t', t);
                               if isError t' then
                                   (TList (TError, loc), loc)
                               else
@@ -356,8 +368,8 @@ fun checkExp G (eAll as (e, loc)) =
                val tf = checkExp G func
                val ta = checkExp G arg
            in
-               (subTyp (tf, (TArrow (dom, ran), loc));
-                subTyp (ta, dom)
+               (hasTyp (func, tf, (TArrow (dom, ran), loc));
+                hasTyp (arg, ta, dom)
                 handle Unify ue =>
                        dte (WrongType ("Function argument",
                                        arg,
@@ -637,7 +649,7 @@ fun checkDecl G (d, _, loc) =
 
            val t = checkExp G e
        in
-           subTyp (t, to)
+           hasTyp (e, t, to)
            handle Unify ue =>
                   describe_type_error loc
                                       (WrongType ("Bound value",
@@ -658,7 +670,7 @@ fun checkFile G tInit (ds, eo) =
            let
                val t = checkExp G' e
            in
-               subTyp (t, tInit)
+               hasTyp (e, t, tInit)
                handle Unify ue =>
                       (ErrorMsg.error (SOME loc) "Bad type for final expression of source file.";
                        preface ("Actual:", p_typ t);