X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcExpr.lhs;h=79b097e38a9aab97484833f489166e6c654cb84a;hb=37a6a52facd1c3999ce4472c50b0030568be1e04;hp=297b4e884e924411667c44dd283f13a92c481604;hpb=0c1a685f5727c8516ec3f06806bc3b0ae0be2370;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcExpr.lhs b/compiler/typecheck/TcExpr.lhs
index 297b4e8..79b097e 100644
--- a/compiler/typecheck/TcExpr.lhs
+++ b/compiler/typecheck/TcExpr.lhs
@@ -45,15 +45,18 @@ import Type
 import Coercion
 import Var
 import VarSet
+import VarEnv
 import TysWiredIn
 import TysPrim( intPrimTy )
 import PrimOp( tagToEnumKey )
 import PrelNames
+import Module
 import DynFlags
 import SrcLoc
 import Util
 import ListSetOps
 import Maybes
+import ErrUtils
 import Outputable
 import FastString
 import Control.Monad
@@ -82,7 +85,7 @@ tcPolyExpr expr res_ty
 
 tcPolyExprNC expr res_ty
   = do { traceTc "tcPolyExprNC" (ppr res_ty)
-       ; (gen_fn, expr') <- tcGen (GenSkol res_ty) res_ty $ \ _ rho ->
+       ; (gen_fn, expr') <- tcGen GenSigCtxt res_ty $ \ _ rho ->
 			    tcMonoExprNC expr rho
        ; return (mkLHsWrap gen_fn expr') }
 
@@ -191,7 +194,7 @@ tcExpr (ExprWithTySig expr sig_ty) res_ty
 
       -- Remember to extend the lexical type-variable environment
       ; (gen_fn, expr') 
-            <- tcGen (SigSkol ExprSigCtxt) sig_tc_ty $ \ skol_tvs res_ty ->
+            <- tcGen ExprSigCtxt sig_tc_ty $ \ skol_tvs res_ty ->
       	       tcExtendTyVarEnv2 (hsExplicitTvs sig_ty `zip` mkTyVarTys skol_tvs) $
 	             	       	-- See Note [More instantiated than scoped] in TcBinds
       	       tcMonoExprNC expr res_ty
@@ -414,8 +417,8 @@ tcExpr (HsIf (Just fun) pred b1 b2) res_ty   -- Note [Rebindable syntax for if]
        -- and it maintains uniformity with other rebindable syntax
        ; return (HsIf (Just fun') pred' b1' b2') }
 
-tcExpr (HsDo do_or_lc stmts body _) res_ty
-  = tcDoStmts do_or_lc stmts body res_ty
+tcExpr (HsDo do_or_lc stmts _) res_ty
+  = tcDoStmts do_or_lc stmts res_ty
 
 tcExpr (HsProc pat cmd) res_ty
   = do	{ (pat', cmd', coi) <- tcProc pat cmd res_ty
@@ -737,7 +740,7 @@ tcExpr (PArrSeq _ seq@(FromTo expr1 expr2)) res_ty
 	; expr1' <- tcPolyExpr expr1 elt_ty
 	; expr2' <- tcPolyExpr expr2 elt_ty
 	; enum_from_to <- newMethodFromName (PArrSeqOrigin seq) 
-				 enumFromToPName elt_ty 
+				 (enumFromToPName basePackageId) elt_ty    -- !!!FIXME: chak
 	; return $ mkHsWrapCoI coi 
                      (PArrSeq enum_from_to (FromTo expr1' expr2')) }
 
@@ -747,7 +750,7 @@ tcExpr (PArrSeq _ seq@(FromThenTo expr1 expr2 expr3)) res_ty
 	; expr2' <- tcPolyExpr expr2 elt_ty
 	; expr3' <- tcPolyExpr expr3 elt_ty
 	; eft <- newMethodFromName (PArrSeqOrigin seq)
-		      enumFromThenToPName elt_ty
+		      (enumFromThenToPName basePackageId) elt_ty        -- !!!FIXME: chak
 	; return $ mkHsWrapCoI coi 
                      (PArrSeq eft (FromThenTo expr1' expr2' expr3')) }
 
@@ -819,7 +822,8 @@ tcApp fun args res_ty
 	-- Typecheck the result, thereby propagating 
         -- info (if any) from result into the argument types
         -- Both actual_res_ty and res_ty are deeply skolemised
-        ; co_res <- unifyType actual_res_ty res_ty
+        ; co_res <- addErrCtxtM (funResCtxt fun actual_res_ty res_ty) $
+                    unifyType actual_res_ty res_ty
 
 	-- Typecheck the arguments
 	; args1 <- tcArgs fun args expected_arg_tys
@@ -1384,6 +1388,24 @@ funAppCtxt fun arg arg_no
 		    quotes (ppr fun) <> text ", namely"])
        2 (quotes (ppr arg))
 
+funResCtxt :: LHsExpr Name -> TcType -> TcType 
+           -> TidyEnv -> TcM (TidyEnv, Message)
+-- When we have a mis-match in the return type of a function
+-- try to give a helpful message about too many/few arguments
+funResCtxt fun fun_res_ty res_ty env0
+  = do { fun_res' <- zonkTcType fun_res_ty
+       ; res'     <- zonkTcType res_ty
+       ; let n_fun = length (fst (tcSplitFunTys fun_res'))
+             n_res = length (fst (tcSplitFunTys res'))
+             what  | n_fun > n_res = ptext (sLit "few")
+                   | otherwise     = ptext (sLit "many")
+             extra | n_fun == n_res = empty
+                   | otherwise = ptext (sLit "Probable cause:") <+> quotes (ppr fun)
+                                 <+> ptext (sLit "is applied to too") <+> what 
+                                 <+> ptext (sLit "arguments") 
+             msg = ptext (sLit "In the return type of a call of") <+> quotes (ppr fun)
+       ; return (env0, msg $$ extra) }
+
 badFieldTypes :: [(Name,TcType)] -> SDoc
 badFieldTypes prs
   = hang (ptext (sLit "Record update for insufficiently polymorphic field")