Improve error reporting for SigTvs, and add comments

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

diff --git a/compiler/typecheck/TcUnify.lhs b/compiler/typecheck/TcUnify.lhs
index eba9985..649408c 100644 (file)
--- a/compiler/typecheck/TcUnify.lhs
+++ b/compiler/typecheck/TcUnify.lhs
@@ -48,9 +48,9 @@ import TcType         ( TcKind, TcType, TcTyVar, BoxyTyVar, TcTauType,
                          tcSplitForAllTys, tcSplitAppTy_maybe, tcSplitFunTys, mkTyVarTys,
                          tcSplitSigmaTy, tyVarsOfType, mkPhiTy, mkTyVarTy, mkPredTy, 
                          typeKind, mkForAllTys, mkAppTy, isBoxyTyVar,
-                         exactTyVarsOfType, 
+                         tcView, exactTyVarsOfType, 
                          tidyOpenType, tidyOpenTyVar, tidyOpenTyVars,
-                         pprType, tidyKind, tidySkolemTyVar, isSkolemTyVar, tcView, 
+                         pprType, tidyKind, tidySkolemTyVar, isSkolemTyVar, isSigTyVar,
                          TvSubst, mkTvSubst, zipTyEnv, zipOpenTvSubst, emptyTvSubst, 
                          substTy, substTheta, 
                          lookupTyVar, extendTvSubst )
@@ -1501,8 +1501,8 @@ ppr_ty env ty
             simple_result  = (env1, quotes (ppr tidy_ty), empty)
        ; case tidy_ty of
           TyVarTy tv 
-               | isSkolemTyVar tv -> return (env2, pp_rigid tv',
-                                             pprSkolTvBinding tv')
+               | isSkolemTyVar tv || isSigTyVar tv
+               -> return (env2, pp_rigid tv', pprSkolTvBinding tv')
                | otherwise -> return simple_result
                where
                  (env2, tv') = tidySkolemTyVar env1 tv