[project @ 2001-04-14 07:36:58 by lewie]

Fix a couple of bugs affecting implicit params.  With implicit params, you
can have a rho type w/o being a forall type.

diff --git a/ghc/compiler/typecheck/TcType.lhs b/ghc/compiler/typecheck/TcType.lhs
index f332114..2cee03e 100644 (file)
--- a/ghc/compiler/typecheck/TcType.lhs
+++ b/ghc/compiler/typecheck/TcType.lhs
@@ -188,7 +188,8 @@ fresh type variables, splits off the dictionary part, and returns the results.
 tcInstType :: TcType -> NF_TcM ([TcTyVar], TcThetaType, TcType)
 tcInstType ty
   = case splitForAllTys ty of
-       ([],     _)   -> returnNF_Tc ([], [], ty)        -- Nothing to do
+       ([],     rho) -> tcSplitRhoTy rho                       `thenNF_Tc` \ (theta, tau) ->
+                        returnNF_Tc ([], theta, tau)
        (tyvars, rho) -> tcInstTyVars tyvars                    `thenNF_Tc` \ (tyvars', _, tenv)  ->
                         tcSplitRhoTy (substTy tenv rho)        `thenNF_Tc` \ (theta, tau) ->
                         returnNF_Tc (tyvars', theta, tau)

diff --git a/ghc/compiler/types/PprType.lhs b/ghc/compiler/types/PprType.lhs
index 6e4d5d0..273a067 100644 (file)
--- a/ghc/compiler/types/PprType.lhs
+++ b/ghc/compiler/types/PprType.lhs
@@ -22,7 +22,7 @@ import TypeRep                ( Type(..), TyNote(..), Kind, liftedTypeKind ) -- friend
 import Type            ( PredType(..), ThetaType,
                          splitPredTy_maybe,
                          splitForAllTys, splitSigmaTy, splitRhoTy,
-                         isDictTy, splitTyConApp_maybe, splitFunTy_maybe,
+                         isPredTy, isDictTy, splitTyConApp_maybe, splitFunTy_maybe,
                           predRepTy, isUTyVar
                        )
 import Var             ( TyVar, tyVarKind )
@@ -189,8 +189,10 @@ ppr_ty ctxt_prec (FunTy ty1 ty2)
   -- so we mustn't use splitFunTys here.
   = maybeParen ctxt_prec fUN_PREC $
     sep [ ppr_ty fUN_PREC ty1
-        , ptext SLIT("->") <+> ppr_ty tOP_PREC ty2
+        , ptext arrow <+> ppr_ty tOP_PREC ty2
         ]
+  where arrow | isPredTy ty1 = SLIT("=>")
+             | otherwise    = SLIT("->")
 
 ppr_ty ctxt_prec (AppTy ty1 ty2)
   = maybeParen ctxt_prec tYCON_PREC $