You can just write the instance of Typeable by hand instance Typeable1 e => Typeable (Y e) where ... (Use the instances in the library as a guide.) Yes, GHC could do this for you, but it would then stumble when e had kind ((*->*) -> *). We need kind polymorphism! Simon | -----Original Message----- | From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell-users- | bounces@haskell.org] On Behalf Of John Meacham | Sent: 02 June 2004 21:53 | To: glasgow-haskell-users@haskell.org | Subject: deriving Typeable | | newtype Y e = Y { unY :: (e (Y e)) } | deriving(Data,Typeable,Show,Read,Eq) | | gives | E.hs:64: | Can't make a derived instance of `Typeable (Y e)' | (`Y' is parameterised over arguments of kind other than `*') | When deriving instances for type `Y' | | Is there any way around this limitation other than manually expanding Y | everywhere I want to use it (which I really don't want to do)? Is the | limitation inherent to the way Typeable works, or is it just that no one | has implemented it yet? | | -- | John Meacham - ⑆repetae.net⑆john⑈ | _______________________________________________ | Glasgow-haskell-users mailing list | Glasgow-haskell-users@haskell.org | http://www.haskell.org/mailman/listinfo/glasgow-haskell-users