- NewTypes
-%* *
-%************************************************************************
-
-\begin{code}
-splitRecNewType_maybe :: Type -> Maybe Type
--- Sometimes we want to look through a recursive newtype, and that's what happens here
--- It only strips *one layer* off, so the caller will usually call itself recursively
--- Only applied to types of kind *, hence the newtype is always saturated
-splitRecNewType_maybe ty | Just ty' <- coreView ty = splitRecNewType_maybe ty'
-splitRecNewType_maybe (TyConApp tc tys)
- | isClosedNewTyCon tc
- = ASSERT( tys `lengthIs` tyConArity tc ) -- splitRecNewType_maybe only be applied
- -- to *types* (of kind *)
- ASSERT( isRecursiveTyCon tc ) -- Guaranteed by coreView
- case newTyConRhs tc of
- (tvs, rep_ty) -> ASSERT( length tvs == length tys )
- Just (substTyWith tvs tys rep_ty)
-
-splitRecNewType_maybe other = Nothing
-
-
-
-\end{code}
-
-
-%************************************************************************
-%* *