Is it possible in Haskell to define a type class like Show, which has a generic implementation for Lists and a special one for [Char], but (in contrast to Show) where Char is not in this Class I'd like to have something like the following, but this example doesn't work: ------------------------------------------- module Test where class Foo a where foo :: a -> a .... .... instance FooList a => Foo [a] where foo lst = fooList lst .... .... class FooList a where fooList :: [a] -> [a] .... .... genericImpl :: Foo a => [a] -> [a] genericImpl = ... specialImpl :: String -> String specialImpl = .... instance FooList Char where fooList s = specialImpl s ..... instance Foo a => FooList a where fooList lst = genericImpl lst ..... --------------------------------------------- Hugs sais ERROR Test.hs:20 - syntax error in instance head (constructor expected) ghc (5.00) sais Test.hs:20: Illegal instance declaration for `FooList a' (the instance type must be of form (T a b c) where T is not a synonym, and a,b,c are distinct type variables) is there a better way, than to copy the instance declaration of FooList for every a in that is in class Foo? Thanks for any hint, Markus -- Markus Lauer <Markus.Lauer@lauer-edv.com>