isForeignTyCon :: TyCon -> Bool
-- isForeignTyCon identifies foreign-imported type constructors
--- For the moment, they are primitive but lifted, but that may change
-isForeignTyCon (PrimTyCon {isUnLifted = is_unlifted}) = not is_unlifted
-isForeignTyCon other = False
+isForeignTyCon (PrimTyCon {tyConExtName = Just _}) = True
+isForeignTyCon other = False
\end{code}
\begin{code}