X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypecheck%2FTcPat.lhs;h=9d4c9b0c1187ecdd1392ccaa003ac9838c651959;hb=d5c0de4518422315f0179121b222b0e3c7d82d86;hp=e7fd6ca6d1c939a86acfc85ab7bfad6bba24f431;hpb=8ffdb8eed6b38db00761093889f5cddbe8ca1d60;p=ghc-hetmet.git

diff --git a/compiler/typecheck/TcPat.lhs b/compiler/typecheck/TcPat.lhs
index e7fd6ca..9d4c9b0 100644
--- a/compiler/typecheck/TcPat.lhs
+++ b/compiler/typecheck/TcPat.lhs
@@ -228,7 +228,7 @@ unBoxArgType ty pp_this
 
 Note [Nesting]
 ~~~~~~~~~~~~~~
-tcPat takes a "thing inside" over which the patter scopes.  This is partly
+tcPat takes a "thing inside" over which the pattern scopes.  This is partly
 so that tcPat can extend the environment for the thing_inside, but also 
 so that constraints arising in the thing_inside can be discharged by the
 pattern.
@@ -546,7 +546,7 @@ 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	{ let (univ_tvs, ex_tvs, eq_spec, theta, arg_tys) = dataConFullSig data_con
+  = do	{ let (univ_tvs, ex_tvs, eq_spec, theta, arg_tys, _) = dataConFullSig data_con
 	      skol_info = PatSkol data_con
 	      origin    = SigOrigin skol_info
 
@@ -583,9 +583,8 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
 	     ex_tvs' ++ inner_tvs, res)
 	}
   where
-    -- Split against the family tycon if the pattern constructor belongs to a
-    -- representation tycon.
-    --
+    -- Split against the family tycon if the pattern constructor 
+    -- belongs to a family instance tycon.
     boxySplitTyConAppWithFamily tycon pat_ty =
       traceTc traceMsg >>
       case tyConFamInst_maybe tycon of
@@ -813,6 +812,19 @@ tcOverloadedLit orig lit@(HsFractional r fr) res_ty
   = do 	{ expr <- newLitInst orig lit res_ty
 	; return (HsFractional r expr) }
 
+tcOverloadedLit orig lit@(HsIsString s fr) res_ty
+  | not (fr `isHsVar` fromStringName)	-- c.f. HsIntegral case
+  = do	{ str_ty <- tcMetaTy stringTyConName
+	; fr' <- tcSyntaxOp orig fr (mkFunTy str_ty res_ty)
+	; return (HsIsString s (HsApp (noLoc fr') (nlHsLit (HsString s)))) }
+
+  | Just expr <- shortCutStringLit s res_ty 
+  = return (HsIsString s expr)
+
+  | otherwise
+  = do 	{ expr <- newLitInst orig lit res_ty
+	; return (HsIsString s expr) }
+
 newLitInst :: InstOrigin -> HsOverLit Name -> BoxyRhoType -> TcM (HsExpr TcId)
 newLitInst orig lit res_ty	-- Make a LitInst
   = do 	{ loc <- getInstLoc orig