(F)SLIT -> (f)sLit in TcTyFuns

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

diff --git a/compiler/typecheck/TcTyFuns.lhs b/compiler/typecheck/TcTyFuns.lhs
index 82e397f..4c5be1c 100644 (file)
--- a/compiler/typecheck/TcTyFuns.lhs
+++ b/compiler/typecheck/TcTyFuns.lhs
@@ -7,8 +7,6 @@ module TcTyFuns (
 
        normaliseGivenEqs, normaliseGivenDicts, 
        normaliseWantedEqs, normaliseWantedDicts,
-       solveWantedEqs,
-       substEqInDictInsts,
        
         -- errors
         misMatchMsg, failWithMisMatch
@@ -37,6 +35,7 @@ import Bag
 import Outputable
 import SrcLoc  ( Located(..) )
 import Maybes
+import FastString
 
 -- standard
 import Data.List
@@ -231,10 +230,6 @@ tcGenericNormaliseFamInst fun (ForAllTy tyvar ty1)
   = do         { (coi,nty1) <- tcGenericNormaliseFamInst fun ty1
        ; return (mkForAllTyCoI tyvar coi, mkForAllTy tyvar nty1)
        }
-tcGenericNormaliseFamInst fun (NoteTy note ty1)
-  = do { (coi,nty1) <- tcGenericNormaliseFamInst fun ty1
-       ; return (coi, NoteTy note nty1)
-       }
 tcGenericNormaliseFamInst fun ty@(TyVarTy tv)
   | isTcTyVar tv
   = do { traceTc (text "tcGenericNormaliseFamInst" <+> ppr ty)
@@ -311,38 +306,12 @@ normaliseGivenEqs givens
 \end{code}
 
 \begin{code}
-normaliseWantedEqs :: [Inst] -> TcM [Inst]
-normaliseWantedEqs insts 
-  = do { traceTc (text "normaliseWantedEqs <-" <+> ppr insts)
-       ; result <- liftM fst $ rewriteToFixedPoint Nothing
-                    [ ("(ZONK)",    dontRerun $ zonkInsts)
-                    , ("(TRIVIAL)", dontRerun $ trivialRule)
-                    , ("(DECOMP)",  decompRule)
-                    , ("(TOP)",     topRule)
-                    , ("(UNIFY)",   unifyMetaRule)      -- incl. occurs check
-                    , ("(SUBST)",   substRule)          -- incl. occurs check
-                     ] insts
-       ; traceTc (text "normaliseWantedEqs ->" <+> ppr result)
-       ; return result
-       }
-\end{code}
-
-
-%************************************************************************
-%*                                                                     *
-\section{Solving of wanted constraints with respect to a given set}
-%*                                                                     *
-%************************************************************************
-
-The set of given equalities must have been normalised already.
-
-\begin{code}
-solveWantedEqs :: [Inst]        -- givens
-            -> [Inst]          -- wanteds
-            -> TcM [Inst]      -- irreducible wanteds
-solveWantedEqs givens wanteds 
-  = do { traceTc $ text "solveWantedEqs <-" <+> ppr wanteds <+> text "with" <+> 
-                   ppr givens
+normaliseWantedEqs :: [Inst]        -- givens
+                  -> [Inst]        -- wanteds
+                  -> TcM [Inst]    -- irreducible wanteds
+normaliseWantedEqs givens wanteds 
+  = do { traceTc $ text "normaliseWantedEqs <-" <+> ppr wanteds 
+                   <+> text "with" <+> ppr givens
        ; result <- liftM fst $ rewriteToFixedPoint Nothing
                      [ ("(ZONK)",    dontRerun $ zonkInsts)
                      , ("(TRIVIAL)", dontRerun $ trivialRule)
@@ -350,8 +319,9 @@ solveWantedEqs givens wanteds
                      , ("(TOP)",     topRule)
                      , ("(GIVEN)",   substGivens givens) -- incl. occurs check
                      , ("(UNIFY)",   unifyMetaRule)      -- incl. occurs check
+                    , ("(SUBST)",   substRule)          -- incl. occurs check
                      ] wanteds
-       ; traceTc (text "solveWantedEqs ->" <+> ppr result)
+       ; traceTc (text "normaliseWantedEqs ->" <+> ppr result)
        ; return result
        }
   where
@@ -986,26 +956,30 @@ unifyMetaRule insts
         uMeta _swapped _tv (IndirectTv _) _ty _cotv
           = return ([inst], False)
 
-        -- signature skolem meets non-variable type
-        -- => cannot update!
-        uMeta _swapped _tv (DoneTv (MetaTv (SigTv _) _)) ty _cotv
-          | not $ isTyVarTy ty
-          = return ([inst], False)
-
         -- type variable meets type variable
         -- => check that tv2 hasn't been updated yet and choose which to update
        uMeta swapped tv1 (DoneTv details1) (TyVarTy tv2) cotv
+         | tv1 == tv2
+         = return ([inst], False)      -- The two types are already identical
+
+         | otherwise
          = do { lookupTV2 <- lookupTcTyVar tv2
                ; case lookupTV2 of
-                   IndirectTv ty  -> uMeta swapped tv1 (DoneTv details1) ty cotv
-                   DoneTv details2 -> 
-                     uMetaVar swapped tv1 details1 tv2 details2 cotv
+                   IndirectTv ty   -> uMeta swapped tv1 (DoneTv details1) ty cotv
+                   DoneTv details2 -> uMetaVar swapped tv1 details1 tv2 details2 cotv
               }
 
+       ------ Beyond this point we know that ty2 is not a type variable
+
+        -- signature skolem meets non-variable type
+        -- => cannot update!
+        uMeta _swapped _tv (DoneTv (MetaTv (SigTv _) _)) _non_tv_ty _cotv
+          = return ([inst], False)
+
         -- updatable meta variable meets non-variable type
         -- => occurs check, monotype check, and kinds match check, then update
-       uMeta swapped tv (DoneTv (MetaTv _ ref)) ty cotv
-         = do { mb_ty' <- checkTauTvUpdate tv ty    -- occurs + monotype check
+       uMeta swapped tv (DoneTv (MetaTv _ ref)) non_tv_ty cotv
+         = do { mb_ty' <- checkTauTvUpdate tv non_tv_ty    -- occurs + monotype check
                ; case mb_ty' of
                    Nothing  -> return ([inst], False)  -- tv occurs in faminst
                    Just ty' ->
@@ -1017,6 +991,7 @@ unifyMetaRule insts
 
         uMeta _ _ _ _ _ = panic "uMeta"
 
+       -- uMetaVar: unify two type variables
         -- meta variable meets skolem 
         -- => just update
         uMetaVar swapped tv1 (MetaTv _ ref) tv2 (SkolemTv _) cotv
@@ -1177,7 +1152,7 @@ genericNormaliseInsts isWanted fun insts
                              --        else
                              --          dict' = dict  `cast` co
                          expr      = HsVar $ instToId source_dict
-                         cast_expr = HsWrap (WpCo st_co) expr
+                         cast_expr = HsWrap (WpCast st_co) expr
                          rhs       = L (instLocSpan loc) cast_expr
                          binds     = instToDictBind target_dict rhs
                      -- return the new inst
@@ -1236,9 +1211,9 @@ misMatchMsg :: TidyEnv -> (TcType, TcType) -> (TidyEnv, SDoc)
 misMatchMsg env0 (ty_act, ty_exp)
   = let (env1, pp_exp, extra_exp) = ppr_ty env0 ty_exp
        (env2, pp_act, extra_act) = ppr_ty env1 ty_act
-        msg = sep [sep [ptext SLIT("Couldn't match expected type") <+> pp_exp, 
+        msg = sep [sep [ptext (sLit "Couldn't match expected type") <+> pp_exp, 
                        nest 7 $
-                              ptext SLIT("against inferred type") <+> pp_act],
+                              ptext (sLit "against inferred type") <+> pp_act],
                   nest 2 (extra_exp $$ extra_act)]
     in
     (env2, msg)