Generics and type classes

[MR K P SCHUPKE]

Because the 'cast' operator used in generics, works on having a concrete
type to cast to. What you need to do is:

module TypeTest where

import Data.Generics

class Data a => MyClass a

instance MyClass ExampleType1
instance MyClass ExampleType2

special :: ExampleType1 -> ExampleType1
special = ...

special2 :: ExampleType2 -> ExampleType2
special2 = ...

generic :: MyClass a => a -> a
generic = everywhere (mkT special `extT` special2 ...)

	Regards,
	Keean.