X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Ftypes%2FTyCon.lhs;h=b3596609e77029695187852b64e7b53ccbb1add9;hb=27ca67931713c36f5ed248de88298416892e5649;hp=d536f59a6a79e61abbaa05c72f47ea53bc33edd8;hpb=d5c4754dcb857be7b9f4dbf6482e6050a9cd0991;p=ghc-hetmet.git

diff --git a/compiler/types/TyCon.lhs b/compiler/types/TyCon.lhs
index d536f59..b359660 100644
--- a/compiler/types/TyCon.lhs
+++ b/compiler/types/TyCon.lhs
@@ -14,11 +14,12 @@ module TyCon(
 	SynTyConRhs(..),
 
 	isFunTyCon, isUnLiftedTyCon, isProductTyCon, 
-	isAlgTyCon, isDataTyCon, isSynTyCon, isNewTyCon, isPrimTyCon,
+	isAlgTyCon, isDataTyCon, isSynTyCon, isNewTyCon, isClosedNewTyCon,
+	isPrimTyCon, 
 	isEnumerationTyCon, isGadtSyntaxTyCon, isOpenTyCon,
 	assocTyConArgPoss_maybe, isTyConAssoc, setTyConArgPoss,
 	isTupleTyCon, isUnboxedTupleTyCon, isBoxedTupleTyCon, tupleTyConBoxity,
-	isRecursiveTyCon, newTyConRep, newTyConRhs, newTyConCo,
+	isRecursiveTyCon, newTyConRep, newTyConRhs, newTyConCo_maybe,
 	isHiBootTyCon, isSuperKindTyCon,
         isCoercionTyCon_maybe, isCoercionTyCon,
 
@@ -100,6 +101,8 @@ data TyCon
 	tyConTyVars :: [TyVar],		-- Scopes over (a) the algTcStupidTheta
 					--	       (b) the cached types in
 					--		   algTyConRhs.NewTyCon
+					--	       (c) the family instance
+					--		   types if present
 					-- But not over the data constructors
 
         tyConArgPoss :: Maybe [Int],    -- for associated families: for each
@@ -560,6 +563,14 @@ isNewTyCon (AlgTyCon {algTcRhs = rhs}) = case rhs of
 					   _	        -> False
 isNewTyCon other			= False
 
+-- This is an important refinement as typical newtype optimisations do *not*
+-- hold for newtype families.  Why?  Given a type `T a', if T is a newtype
+-- family, there is no unique right hand side by which `T a' can be replaced
+-- by a cast.
+--
+isClosedNewTyCon :: TyCon -> Bool
+isClosedNewTyCon tycon = isNewTyCon tycon && not (isOpenTyCon tycon)
+
 isProductTyCon :: TyCon -> Bool
 -- A "product" tycon
 --	has *one* constructor, 
@@ -747,12 +758,9 @@ newTyConRep :: TyCon -> ([TyVar], Type)
 newTyConRep (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_rep = rep }}) = (tvs, rep)
 newTyConRep tycon = pprPanic "newTyConRep" (ppr tycon)
 
-newTyConCo :: TyCon -> Maybe TyCon
-newTyConCo (AlgTyCon {tyConTyVars = tvs, algTcRhs = NewTyCon { nt_co = co }})
-  = co
-newTyConCo (AlgTyCon {tyConTyVars = tvs, algTcRhs = OpenNewTyCon})
-  = Nothing
-newTyConCo tycon = pprPanic "newTyConCo" (ppr tycon)
+newTyConCo_maybe :: TyCon -> Maybe TyCon
+newTyConCo_maybe (AlgTyCon {algTcRhs = NewTyCon { nt_co = co }}) = co
+newTyConCo_maybe _						 = Nothing
 
 tyConPrimRep :: TyCon -> PrimRep
 tyConPrimRep (PrimTyCon {primTyConRep = rep}) = rep
@@ -807,8 +815,8 @@ tyConClass_maybe (AlgTyCon {algTcParent = ClassTyCon clas}) = Just clas
 tyConClass_maybe ther_tycon				    = Nothing
 
 isFamInstTyCon :: TyCon -> Bool
-isFamInstTyCon (AlgTyCon {algTcParent = FamilyTyCon _ _ _}) = True
-isFamInstTyCon other_tycon			            = False
+isFamInstTyCon (AlgTyCon {algTcParent = FamilyTyCon _ _ _ }) = True
+isFamInstTyCon other_tycon			             = False
 
 tyConFamInst_maybe :: TyCon -> Maybe (TyCon, [Type])
 tyConFamInst_maybe (AlgTyCon {algTcParent = FamilyTyCon fam instTys _}) =