Use implication constraints to improve type inference

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

diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs
index c9b5d6e..933adb8 100644 (file)
--- a/compiler/typecheck/TcPat.lhs
+++ b/compiler/typecheck/TcPat.lhs
@@ -531,14 +531,14 @@ tcConPat :: PatState -> SrcSpan -> DataCon -> TyCon
         -> HsConDetails Name (LPat Name) -> (PatState -> TcM a)
         -> TcM (Pat TcId, [TcTyVar], a)
 tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
-  = do { span <- getSrcSpanM   -- Span for the whole pattern
-       ; let (univ_tvs, ex_tvs, eq_spec, theta, arg_tys) = dataConFullSig data_con
-             skol_info = PatSkol data_con span
+  = do { let (univ_tvs, ex_tvs, eq_spec, theta, arg_tys) = dataConFullSig data_con
+             skol_info = PatSkol data_con
              origin    = SigOrigin skol_info
 
          -- Instantiate the constructor type variables [a->ty]
        ; ctxt_res_tys <- boxySplitTyConAppWithFamily tycon pat_ty
-       ; ex_tvs' <- tcInstSkolTyVars skol_info ex_tvs
+       ; ex_tvs' <- tcInstSkolTyVars skol_info ex_tvs  -- Get location from monad,
+                                                       -- not from ex_tvs
        ; let tenv     = zipTopTvSubst (univ_tvs ++ ex_tvs)
                                      (ctxt_res_tys ++ mkTyVarTys ex_tvs')
              eq_spec' = substEqSpec tenv eq_spec
@@ -553,7 +553,8 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
 
        ; loc <- getInstLoc origin
        ; dicts <- newDictBndrs loc theta'
-       ; dict_binds <- tcSimplifyCheck doc ex_tvs' dicts lie_req
+       ; dict_binds <- tcSimplifyCheckPat loc co_vars (pat_reft pstate') 
+                                          ex_tvs' dicts lie_req
 
        ; addDataConStupidTheta data_con ctxt_res_tys
 
@@ -567,8 +568,6 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
             ex_tvs' ++ inner_tvs, res)
        }
   where
-    doc = ptext SLIT("existential context for") <+> quotes (ppr data_con)
-
     -- Split against the family tycon if the pattern constructor belongs to a
     -- representation tycon.
     --