[project @ 2004-12-20 17:16:24 by simonpj]

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

diff --git a/ghc/compiler/typecheck/TcBinds.lhs b/ghc/compiler/typecheck/TcBinds.lhs
index 9db0b3a..ad5060b 100644 (file)
--- a/ghc/compiler/typecheck/TcBinds.lhs
+++ b/ghc/compiler/typecheck/TcBinds.lhs
@@ -50,6 +50,7 @@ import VarSet
 import SrcLoc          ( Located(..), unLoc, noLoc, getLoc )
 import Bag
 import Util            ( isIn )
+import Maybes          ( orElse )
 import BasicTypes      ( TopLevelFlag(..), RecFlag(..), isNonRec, isRec, 
                          isNotTopLevel, isAlwaysActive )
 import FiniteMap       ( listToFM, lookupFM )
@@ -567,7 +568,7 @@ tcTySig sig1 (L span (Sig (L _ name) ty))
 
        -- Try to match the context of this signature with 
        -- that of the first signature
-       ; case tcMatchPreds tvs (sig_theta sig1) theta of { 
+       ; case tcMatchPreds tvs theta (sig_theta sig1) of { 
            Nothing   -> bale_out
        ;   Just tenv -> do
        ; case check_tvs tenv tvs of
@@ -593,15 +594,12 @@ tcTySig sig1 (L span (Sig (L _ name) ty))
     check_tvs :: TvSubstEnv -> [TcTyVar] -> Maybe [TcTyVar]
     check_tvs tenv [] = Just []
     check_tvs tenv (tv:tvs) 
-       | Just ty <- lookupVarEnv tenv tv
-       = do { tv' <- tcGetTyVar_maybe ty
+       = do { let ty = lookupVarEnv tenv tv `orElse` mkTyVarTy tv
+            ; tv'  <- tcGetTyVar_maybe ty
             ; tvs' <- check_tvs tenv tvs
             ; if tv' `elem` tvs'
               then Nothing
               else Just (tv':tvs') }
-       | otherwise
-       = do { tvs' <- check_tvs tenv tvs
-            ; Just (tv:tvs') }
 \end{code}
 
 \begin{code}