deriving Typeable

John Meacham john at
Wed Jun 2 16:53:16 EDT 2004

newtype Y e = Y { unY :: (e (Y e)) }

    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 - ⑆⑆john⑈ 

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