towards unboxing through newtypes

[ghc-hetmet.git] / compiler / types / Type.lhs

diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs
index fd8e8c5..c3013ab 100644 (file)
--- a/compiler/types/Type.lhs
+++ b/compiler/types/Type.lhs
@@ -56,7 +56,7 @@ module Type (
        predTypeRep, mkPredTy, mkPredTys,
 
        -- Newtypes
-       splitRecNewType_maybe,
+       splitRecNewType_maybe, newTyConInstRhs,
 
        -- Lifting and boxity
        isUnLiftedType, isUnboxedTupleType, isAlgType, isPrimitiveType,
@@ -410,6 +410,12 @@ splitNewTyConApp_maybe (TyConApp tc tys) = Just (tc, tys)
 splitNewTyConApp_maybe (FunTy arg res)   = Just (funTyCon, [arg,res])
 splitNewTyConApp_maybe other         = Nothing
 
+-- get instantiated newtype rhs, the arguments had better saturate 
+-- the constructor
+newTyConInstRhs :: TyCon -> [Type] -> Type
+newTyConInstRhs tycon tys =
+    let (tvs, ty) = newTyConRhs tycon in substTyWith tvs tys ty
+
 \end{code}