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

[ghc-hetmet.git] / ghc / compiler / typecheck / TcMType.lhs

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