[Haskell-cafe] Derived type definition

Hi, I've tried to simplify as much as possible my problem. Finally, I think I can resume it like that: Suppose these following data types : data Rec a r = Rec a r data RecNil = RecNil data Wrapper a = Wrapper a Then, we can build the following type: type TTest = Rec Int (Rec String RecNil) or this type: type TTestWrapped = Rec (Wrapper Int) (Rec (Wrapper String) RecNil) Is it possible to build TTestWrapped from TTest ? Thx in advance, Antoine.