Improved Easy_domain, with boolean env vars

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

diff --git a/src/tycheck.sml b/src/tycheck.sml
index def1463..d5b3f1e 100644 (file)
--- a/src/tycheck.sml
+++ b/src/tycheck.sml
@@ -571,6 +571,32 @@ fun checkExp G (eAll as (e, loc)) =
 
          | ESkip => (TAction ((CPrefix (CRoot, loc), loc),
                               SM.empty, SM.empty), loc)
+
+         | EIf (e1, e2, e3) =>
+           let
+               val t1 = checkExp G e1
+               val t2 = checkExp G e2
+               val t3 = checkExp G e3
+               val bool = (TBase "bool", loc)
+           in
+               (subTyp (t1, bool))
+               handle Unify ue =>
+                      dte (WrongType ("\"if\" test",
+                                      e1,
+                                      t1,
+                                      bool,
+                                      SOME ue));
+               (subTyp (t2, t3); t3)
+                      handle Unify _ =>
+                             ((subTyp (t3, t2); t2)
+                              handle Unify ue =>
+                                     (dte (WrongType ("\"else\" case",
+                                                      eAll,
+                                                      t3,
+                                                      t2,
+                                                      SOME ue));
+                                      (TError, loc)))
+           end
     end
 
 exception Ununif