Improve formatting of errors, and fix a typo

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

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index 5928630..24cf3f8 100644 (file)
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -442,17 +442,18 @@ pprSkolTvBinding :: TcTyVar -> SDoc
 -- or nothing if we don't have anything useful to say
 pprSkolTvBinding tv
   = ASSERT ( isTcTyVar tv )
-    ppr_details (tcTyVarDetails tv)
+    quotes (ppr tv) <+> ppr_details (tcTyVarDetails tv)
   where
-    ppr_details (MetaTv TauTv _)   = quotes (ppr tv) <+> ptext SLIT("is a meta type variable")
-    ppr_details (MetaTv BoxTv _)   = quotes (ppr tv) <+> ptext SLIT("is a boxy type variable")
+    ppr_details (MetaTv TauTv _)       = ptext SLIT("is a meta type variable")
+    ppr_details (MetaTv BoxTv _)       = ptext SLIT("is a boxy type variable")
     ppr_details (MetaTv (SigTv info) _) = ppr_skol info
     ppr_details (SkolemTv info)                = ppr_skol info
 
-    ppr_skol UnkSkol = empty   -- Unhelpful; omit
-    ppr_skol RuntimeUnkSkol = quotes (ppr tv) <+> ptext SLIT("is an unknown runtime type")
-    ppr_skol info    = quotes (ppr tv) <+> ptext SLIT("is bound by") 
-                       <+> sep [pprSkolInfo info, nest 2 (ptext SLIT("at") <+> ppr (getSrcLoc tv))]
+    ppr_skol UnkSkol       = empty     -- Unhelpful; omit
+    ppr_skol RuntimeUnkSkol = ptext SLIT("is an unknown runtime type")
+    ppr_skol info           = sep [ptext SLIT("is a rigid type variable bound by"),
+                                  sep [pprSkolInfo info, 
+                                        nest 2 (ptext SLIT("at") <+> ppr (getSrcLoc tv))]]
  
 pprSkolInfo :: SkolemInfo -> SDoc
 pprSkolInfo (SigSkol ctxt)   = pprUserTypeCtxt ctxt
@@ -715,9 +716,16 @@ tcSplitFunTys ty = case tcSplitFunTy_maybe ty of
                                          (args,res') = tcSplitFunTys res
 
 tcSplitFunTy_maybe :: Type -> Maybe (Type, Type)
-tcSplitFunTy_maybe ty | Just ty' <- tcView ty = tcSplitFunTy_maybe ty'
-tcSplitFunTy_maybe (FunTy arg res)  = Just (arg, res)
-tcSplitFunTy_maybe other           = Nothing
+tcSplitFunTy_maybe ty | Just ty' <- tcView ty           = tcSplitFunTy_maybe ty'
+tcSplitFunTy_maybe (FunTy arg res) | not (isPredTy arg) = Just (arg, res)
+tcSplitFunTy_maybe other                               = Nothing
+       -- Note the (not (isPredTy arg)) guard
+       -- Consider     (?x::Int) => Bool
+       -- We don't want to treat this as a function type!
+       -- A concrete example is test tc230:
+       --      f :: () -> (?p :: ()) => () -> ()
+       --
+       --      g = f () ()
 
 tcSplitFunTysN
        :: TcRhoType