[Haskell-cafe] serialize an unknown type

Hi the list! I have a simple question, how can I serialize/deserialize a structure like this: data InputChoice c deriving Typeable data Event a where InputChoice :: (Eq c, Show c) => [c] -> c -> Event (InputChoice c) (...) I'd like that the values of type "c" get serialized to a String... That's the easy part, but for deserializing, oops! Cheers, Corentin