Hi, I've been using Data.Dynamic but the Typeable requirement doesn't go well with FFI declarations (which don't accept type contexts). This is a little example of what I would like to do: data MyDyn = MyDyn myToDyn :: a -> MyDyn myToDyn = unsafeCoerce myFromDyn :: MyDyn -> a myFromDyn = unsafeCoerce -- this is a type I want to transform back and forth from dynamic -- and store into lists etc etc ... data MyType a b = MyType a b -- This it's "abstract" Generic type (it's contructor should be hidden) data MyGenType = MyGenType MyDyn mt2mgt :: MyType a b -> MyGenType mt2mgt = MyGenType.myToDyn mgt2mt :: MyGentype -> MyType a b mgt2mt (MyGenType dyn) = myfromDyn dyn The question is, ¿if only mt2mgt and mgt2mt are used by the user, would the use of unsafeCoerce be dangerous? Thanks in advance, Alfonso Acosta