X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2Ftypes%2FUnify.lhs;fp=compiler%2Ftypes%2FUnify.lhs;h=9c448ce0653af13079713ebe84b28896ced3781d;hp=38507830ab8523c706196b265590345f9be46813;hb=a10a21dadac041e928ad5dab3810b68ab35bc9bb;hpb=5096055e9aa46a7cc8b5a1292f7094fe588ec4d1

diff --git a/compiler/types/Unify.lhs b/compiler/types/Unify.lhs
index 3850783..9c448ce 100644
--- a/compiler/types/Unify.lhs
+++ b/compiler/types/Unify.lhs
@@ -316,9 +316,8 @@ anything, type functions (incl newtypes) match anything, and only
 distinct data types fail to match.  We can elaborate later.
 
 \begin{code}
-typesCantMatch :: [Type] -> [Type] -> Bool
-typesCantMatch tys1 tys2 = ASSERT( equalLength tys1 tys2 )
-		           or (zipWith cant_match tys1 tys2)
+typesCantMatch :: [(Type,Type)] -> Bool
+typesCantMatch prs = any (\(s,t) -> cant_match s t) prs
   where
     cant_match :: Type -> Type -> Bool
     cant_match t1 t2
@@ -330,7 +329,7 @@ typesCantMatch tys1 tys2 = ASSERT( equalLength tys1 tys2 )
 
     cant_match (TyConApp tc1 tys1) (TyConApp tc2 tys2)
 	| isDataTyCon tc1 && isDataTyCon tc2
-	= tc1 /= tc2 || typesCantMatch tys1 tys2
+	= tc1 /= tc2 || typesCantMatch (zipEqual "typesCantMatch" tys1 tys2)
 
     cant_match (FunTy {}) (TyConApp tc _) = isDataTyCon tc
     cant_match (TyConApp tc _) (FunTy {}) = isDataTyCon tc