X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FType.lhs;h=8dfe475349809ed469452fb07c682b49e0b3bad1;hb=9e7dd142eeddc99ccfa9eada236371b267cfbdbb;hp=3705914140e8d018224c7c8f5b82b387ca745eb4;hpb=d7b56effafe21561a127b318c9cfea2897a053c0;p=ghc-hetmet.git

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index 3705914..8dfe475 100644
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -87,7 +87,7 @@ module Type (
 
 	-- * Type free variables
 	tyVarsOfType, tyVarsOfTypes, tyVarsOfPred, tyVarsOfTheta,
-	typeKind,
+	typeKind, expandTypeSynonyms,
 
 	-- * Tidying type related things up for printing
 	tidyType,      tidyTypes,
@@ -132,7 +132,7 @@ module Type (
 
 	-- * Pretty-printing
 	pprType, pprParendType, pprTypeApp, pprTyThingCategory, pprTyThing, pprForAll,
-	pprPred, pprTheta, pprThetaArrow, pprClassPred, pprKind, pprParendKind,
+	pprPred, pprEqPred, pprTheta, pprThetaArrow, pprClassPred, pprKind, pprParendKind,
 	
 	pprSourceTyCon
     ) where
@@ -281,6 +281,29 @@ tcView (TyConApp tc tys) | Just (tenv, rhs, tys') <- tcExpandTyCon_maybe tc tys
 tcView _                 = Nothing
 
 -----------------------------------------------
+expandTypeSynonyms :: Type -> Type
+-- ^ Expand out all type synonyms.  Actually, it'd suffice to expand out
+-- just the ones that discard type variables (e.g.  type Funny a = Int)
+-- But we don't know which those are currently, so we just expand all.
+expandTypeSynonyms ty 
+  = go ty
+  where
+    go (TyConApp tc tys)
+      | Just (tenv, rhs, tys') <- tcExpandTyCon_maybe tc tys 
+      = go (mkAppTys (substTy (mkTopTvSubst tenv) rhs) tys')
+      | otherwise
+      = TyConApp tc (map go tys)
+    go (TyVarTy tv)    = TyVarTy tv
+    go (AppTy t1 t2)   = AppTy (go t1) (go t2)
+    go (FunTy t1 t2)   = FunTy (go t1) (go t2)
+    go (ForAllTy tv t) = ForAllTy tv (go t)
+    go (PredTy p)      = PredTy (go_pred p)
+
+    go_pred (ClassP c ts)  = ClassP c (map go ts)
+    go_pred (IParam ip t)  = IParam ip (go t)
+    go_pred (EqPred t1 t2) = EqPred (go t1) (go t2)
+
+-----------------------------------------------
 {-# INLINE kindView #-}
 kindView :: Kind -> Maybe Kind
 -- ^ Similar to 'coreView' or 'tcView', but works on 'Kind's
@@ -423,8 +446,8 @@ splitAppTys ty = split ty ty []
 \begin{code}
 mkFunTy :: Type -> Type -> Type
 -- ^ Creates a function type from the given argument and result type
-mkFunTy (PredTy (EqPred ty1 ty2)) res = mkForAllTy (mkWildCoVar (PredTy (EqPred ty1 ty2))) res
-mkFunTy arg res = FunTy arg res
+mkFunTy arg@(PredTy (EqPred {})) res = ForAllTy (mkWildCoVar arg) res
+mkFunTy arg                      res = FunTy    arg               res
 
 mkFunTys :: [Type] -> Type -> Type
 mkFunTys tys ty = foldr mkFunTy ty tys
@@ -658,7 +681,7 @@ typePrimRep ty = case repType ty of
 \begin{code}
 mkForAllTy :: TyVar -> Type -> Type
 mkForAllTy tyvar ty
-  = mkForAllTys [tyvar] ty
+  = ForAllTy tyvar ty
 
 -- | Wraps foralls over the type using the provided 'TyVar's from left to right
 mkForAllTys :: [TyVar] -> Type -> Type