[project @ 1999-06-23 10:38:13 by simonmar]

Make scoped type variables work.

ghc/compiler/parser/ParseUtil.lhs

@@ -182,7 +182,14 @@ checkPat e [] = case e of
 	ELazyPat e	   -> checkPat e [] `thenP` (returnP . LazyPatIn)
 	EAsPat n e	   -> checkPat e [] `thenP` (returnP . AsPatIn n)
         ExprWithTySig e t  -> checkPat e [] `thenP` \e ->
-			      returnP (SigPatIn e t)
+			      -- pattern signatures are parsed as sigtypes,
+			      -- but they aren't explicit forall points.  Hence
+			      -- we have to remove the implicit forall here.
+			      let t' = case t of 
+					  HsForAllTy Nothing [] ty -> ty
+					  other -> other
+			      in
+			      returnP (SigPatIn e t')
 
 	OpApp (HsVar n) (HsVar plus) _ (HsLit k@(HsInt _)) | plus == plus_RDR
 			   -> returnP (NPlusKPatIn n k)

ghc/compiler/parser/RdrHsSyn.lhs

@@ -48,7 +48,9 @@ module RdrHsSyn (
 	RdrNameGenPragmas,
 	RdrNameInstancePragmas,
 	extractHsTyRdrNames, 
-	extractPatsTyVars, extractRuleBndrsTyVars,
+	extractHsTyRdrTyVars,
+	extractPatsTyVars, 
+	extractRuleBndrsTyVars,
  
 	mkOpApp, mkClassDecl, mkClassOpSig,
 
@@ -133,6 +135,9 @@ It's used when making the for-alls explicit.
 extractHsTyRdrNames :: HsType RdrName -> [RdrName]
 extractHsTyRdrNames ty = nub (extract_ty ty [])
 
+extractHsTyRdrTyVars	 :: RdrNameHsType -> [RdrName]
+extractHsTyRdrTyVars ty =  filter isRdrTyVar (extractHsTyRdrNames ty)
+
 extractRuleBndrsTyVars :: [RuleBndr RdrName] -> [RdrName]
 extractRuleBndrsTyVars bndrs = filter isRdrTyVar (nub (foldr go [] bndrs))
                            where
@@ -146,13 +151,14 @@ extract_ctxt ctxt acc = foldr extract_ass acc ctxt
                     where
                       extract_ass (cls, tys) acc = foldr extract_ty (cls : acc) tys
 
-extract_ty (MonoTyApp ty1 ty2)        acc = extract_ty ty1 (extract_ty ty2 acc)
-extract_ty (MonoListTy ty)    acc = extract_ty ty acc
-extract_ty (MonoTupleTy tys _)  acc = foldr extract_ty acc tys
-extract_ty (MonoFunTy ty1 ty2)        acc = extract_ty ty1 (extract_ty ty2 acc)
-extract_ty (MonoDictTy cls tys)       acc = foldr extract_ty (cls : acc) tys
-extract_ty (MonoUsgTy usg ty) acc = extract_ty ty acc
-extract_ty (MonoTyVar tv)       acc = tv : acc
+extract_ty (MonoTyApp ty1 ty2)          acc = extract_ty ty1 (extract_ty ty2 acc)
+extract_ty (MonoListTy ty)              acc = extract_ty ty acc
+extract_ty (MonoTupleTy tys _)          acc = foldr extract_ty acc tys
+extract_ty (MonoFunTy ty1 ty2)          acc = extract_ty ty1 (extract_ty ty2 acc)
+extract_ty (MonoDictTy cls tys)         acc = foldr extract_ty (cls : acc) tys
+extract_ty (MonoUsgTy usg ty)           acc = extract_ty ty acc
+extract_ty (MonoTyVar tv)               acc = tv : acc
+extract_ty (HsForAllTy Nothing ctxt ty) acc = extract_ctxt ctxt (extract_ty ty acc)
 extract_ty (HsForAllTy (Just tvs) ctxt ty) 
                                 acc = acc ++
                                       (filter (`notElem` locals) $
@@ -162,7 +168,7 @@ extract_ty (HsForAllTy (Just tvs) ctxt ty)
 
 
 extractPatsTyVars :: [RdrNamePat] -> [RdrName]
-extractPatsTyVars pats = nub (foldr extract_pat [] pats)
+extractPatsTyVars pats = filter isRdrTyVar (nub (foldr extract_pat [] pats))
 
 extract_pat (SigPatIn pat ty)	   acc = extract_ty ty acc
 extract_pat WildPatIn	      	   acc = acc

ghc/compiler/rename/RnExpr.lhs

@@ -829,8 +829,8 @@ nonStdGuardErr guard
     ) 4 (ppr guard)
 
 patSigErr ty
-  = hang (ptext SLIT("Illegal signature in pattern:") <+> ppr ty)
-	 4 (ptext SLIT("Use -fglasgow-exts to permit it"))
+  =  (ptext SLIT("Illegal signature in pattern:") <+> ppr ty)
+	$$ nest 4 (ptext SLIT("Use -fglasgow-exts to permit it"))
 
 pp_op (op, fix) = hcat [ppr op, space, parens (ppr fix)]
 \end{code}

ghc/compiler/rename/RnSource.lhs

@@ -14,7 +14,7 @@ import HsPragmas
 import HsTypes		( getTyVarName, pprClassAssertion, cmpHsTypes )
 import RdrName		( RdrName, isRdrDataCon, rdrNameOcc, isRdrTyVar )
 import RdrHsSyn		( RdrNameContext, RdrNameHsType, RdrNameConDecl,
-			  extractHsTyRdrNames, extractRuleBndrsTyVars
+			  extractRuleBndrsTyVars, extractHsTyRdrTyVars
 			)
 import RnHsSyn
 import HsCore
@@ -565,13 +565,10 @@ checkConstraints explicit_forall doc forall_tyvars ctxt ty
 	| otherwise	   = addErrRn (ctxtErr explicit_forall doc forall_tyvars ct ty)
 			     `thenRn_` returnRn Nothing
         where
-	  forall_mentioned = foldr ((||) . any (`elem` forall_tyvars) . extractHsTyRdrNames)
+	  forall_mentioned = foldr ((||) . any (`elem` forall_tyvars) . extractHsTyRdrTyVars)
 			     False
 			     tys
 
-freeRdrTyVars	 :: RdrNameHsType -> [RdrName]
-freeRdrTyVars ty =  filter isRdrTyVar (extractHsTyRdrNames ty)
-
 rnHsType :: SDoc -> RdrNameHsType -> RnMS (RenamedHsType, FreeVars)
 
 rnHsType doc (HsForAllTy Nothing ctxt ty)
@@ -580,7 +577,7 @@ rnHsType doc (HsForAllTy Nothing ctxt ty)
 	-- over FV(T) \ {in-scope-tyvars} 
   = getLocalNameEnv		`thenRn` \ name_env ->
     let
-	mentioned_in_tau = freeRdrTyVars ty
+	mentioned_in_tau = extractHsTyRdrTyVars ty
 	forall_tyvars    = filter (not . (`elemFM` name_env)) mentioned_in_tau
     in
     checkConstraints False doc forall_tyvars ctxt ty	`thenRn` \ ctxt' ->
@@ -593,10 +590,10 @@ rnHsType doc (HsForAllTy (Just forall_tyvars) ctxt tau)
 	-- That's only a warning... unless the tyvar is constrained by a 
 	-- context in which case it's an error
   = let
-	mentioned_in_tau  = freeRdrTyVars tau
+	mentioned_in_tau  = extractHsTyRdrTyVars tau
 	mentioned_in_ctxt = nub [tv | (_,tys) <- ctxt,
 				      ty <- tys,
-				      tv <- freeRdrTyVars ty]
+				      tv <- extractHsTyRdrTyVars ty]
 
 	dubious_guys	      = filter (`notElem` mentioned_in_tau) forall_tyvar_names
 		-- dubious = explicitly quantified but not mentioned in tau type