One can do something a bit shorter

instance (Typeable a, Typeable1 m) => Typeable1 (Iteratee a m) where typeOf1 i = mkTyConApp (mkTyCon "Data.Enumerator.Iteratee") [typeOf a, typeOf1 m] where (a,m) = peel i peel :: Iteratee a m w -> (a, m ()) peel = undefined

still a bother to write every time one needs it, but tolerable. Only the signature of 'peel' matters.