X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FhsSyn%2FHsTypes.lhs;h=bbe701624c6886ab064af5137172550fbc0be0f4;hp=1ec096671f11f3bff136651fbc751001e5c8b825;hb=84923cc7de2a93c22a2f72daf9ac863959efae13;hpb=ab22f4e6456820c1b5169d75f5975a94e61f54ce

diff --git a/compiler/hsSyn/HsTypes.lhs b/compiler/hsSyn/HsTypes.lhs
index 1ec0966..bbe7016 100644
--- a/compiler/hsSyn/HsTypes.lhs
+++ b/compiler/hsSyn/HsTypes.lhs
@@ -102,7 +102,8 @@ type HsContext name = [LHsPred name]
 
 type LHsPred name = Located (HsPred name)
 
-data HsPred name = HsClassP name [LHsType name]
+data HsPred name = HsClassP name [LHsType name]		 -- class constraint
+		 | HsEqualP (LHsType name) (LHsType name)-- equality constraint
 		 | HsIParam (IPName name) (LHsType name)
 
 type LHsType name = Located (HsType name)
@@ -268,9 +269,6 @@ splitHsFunType other 	   	   = ([], other)
 %*									*
 %************************************************************************
 
-NB: these types get printed into interface files, so 
-    don't change the printing format lightly
-
 \begin{code}
 instance (OutputableBndr name) => Outputable (HsType name) where
     ppr ty = pprHsType ty
@@ -280,8 +278,13 @@ instance (Outputable name) => Outputable (HsTyVarBndr name) where
     ppr (KindedTyVar name kind) = pprHsTyVarBndr name kind
 
 instance OutputableBndr name => Outputable (HsPred name) where
-    ppr (HsClassP clas tys) = ppr clas <+> hsep (map (pprParendHsType.unLoc) tys)
-    ppr (HsIParam n ty)    = hsep [ppr n, dcolon, ppr ty]
+    ppr (HsClassP clas tys) = ppr clas <+> hsep (map pprLHsType tys)
+    ppr (HsEqualP t1 t2)    = hsep [pprLHsType t1, ptext SLIT("~"), 
+				    pprLHsType t2]
+    ppr (HsIParam n ty)     = hsep [ppr n, dcolon, ppr ty]
+
+pprLHsType :: OutputableBndr name => LHsType name -> SDoc
+pprLHsType = pprParendHsType . unLoc
 
 pprHsTyVarBndr :: Outputable name => name -> Kind -> SDoc
 pprHsTyVarBndr name kind | isLiftedTypeKind kind = ppr name
@@ -339,7 +342,6 @@ ppr_mono_ty ctxt_prec (HsForAllTy exp tvs ctxt ty)
   = maybeParen ctxt_prec pREC_FUN $
     sep [pprHsForAll exp tvs ctxt, ppr_mono_lty pREC_TOP ty]
 
--- gaw 2004
 ppr_mono_ty ctxt_prec (HsBangTy b ty)     = ppr b <> ppr ty
 ppr_mono_ty ctxt_prec (HsTyVar name)      = ppr name
 ppr_mono_ty ctxt_prec (HsFunTy ty1 ty2)   = ppr_fun_ty ctxt_prec ty1 ty2
@@ -347,7 +349,7 @@ ppr_mono_ty ctxt_prec (HsTupleTy con tys) = tupleParens con (interpp'SP tys)
 ppr_mono_ty ctxt_prec (HsKindSig ty kind) = parens (ppr_mono_lty pREC_TOP ty <+> dcolon <+> pprKind kind)
 ppr_mono_ty ctxt_prec (HsListTy ty)	  = brackets (ppr_mono_lty pREC_TOP ty)
 ppr_mono_ty ctxt_prec (HsPArrTy ty)	  = pabrackets (ppr_mono_lty pREC_TOP ty)
-ppr_mono_ty ctxt_prec (HsPredTy pred)     = braces (ppr pred)
+ppr_mono_ty ctxt_prec (HsPredTy pred)     = ppr pred
 ppr_mono_ty ctxt_prec (HsNumTy n)         = integer n  -- generics only
 ppr_mono_ty ctxt_prec (HsSpliceTy s)      = pprSplice s