[project @ 2002-03-12 09:12:57 by simonpj]

Comments

diff --git a/ghc/compiler/typecheck/TcMType.lhs b/ghc/compiler/typecheck/TcMType.lhs
index f31746a..1a16e59 100644 (file)
--- a/ghc/compiler/typecheck/TcMType.lhs
+++ b/ghc/compiler/typecheck/TcMType.lhs
@@ -454,6 +454,9 @@ zonkType unbound_var_fn ty
     go (AppTy fun arg)           = go fun              `thenNF_Tc` \ fun' ->
                                    go arg              `thenNF_Tc` \ arg' ->
                                    returnNF_Tc (mkAppTy fun' arg')
+               -- NB the mkAppTy; we might have instantiated a
+               -- type variable to a type constructor, so we need
+               -- to pull the TyConApp to the top.
 
        -- The two interesting cases!
     go (TyVarTy tyvar)     = zonkTyVar unbound_var_fn tyvar

diff --git a/ghc/compiler/typecheck/TcType.lhs b/ghc/compiler/typecheck/TcType.lhs
index 5b9d8ae..5a815e4 100644 (file)
--- a/ghc/compiler/typecheck/TcType.lhs
+++ b/ghc/compiler/typecheck/TcType.lhs
@@ -373,11 +373,11 @@ tcSplitTyConApp ty = case tcSplitTyConApp_maybe ty of
                        Nothing    -> pprPanic "tcSplitTyConApp" (pprType ty)
 
 tcSplitTyConApp_maybe :: Type -> Maybe (TyCon, [Type])
--- Newtypes are opaque, so they may be split
 tcSplitTyConApp_maybe (TyConApp tc tys)        = Just (tc, tys)
 tcSplitTyConApp_maybe (FunTy arg res)          = Just (funTyCon, [arg,res])
 tcSplitTyConApp_maybe (NoteTy n ty)            = tcSplitTyConApp_maybe ty
 tcSplitTyConApp_maybe (SourceTy (NType tc tys)) = Just (tc,tys)
+       -- Newtypes are opaque, so they may be split
        -- However, predicates are not treated
        -- as tycon applications by the type checker
 tcSplitTyConApp_maybe other                    = Nothing