Paramorphisms / Data.Scanable?

I understand that it may not be possible to give simple types to anamorphisms or hylomorphisms, but I don't see there can't be a Data.Scannable with paramorphisms. class Scannable t where scanr :: (a -> b -> b) -> b -> t a -> t b scanl :: (a -> b -> a) -> a -> t b -> t a scanr1 :: (a -> a -> a) -> t a -> t a scanl1 :: (a -> a -> a) -> t a -> t a Jim