http://reasonablypolymorphic.com/blog/higher-kinded-data with one-liner

gvalidate.hs

{-# LANGUAGE FlexibleContexts, FlexibleInstances, TypeApplications, MultiParamTypeClasses, GADTs #-}

import Generics.OneLiner.Binary
import Data.Functor.Identity

class IsMaybe s s' where isMaybe :: s -> Maybe s'
instance (s ~ Maybe s') => IsMaybe s s' where isMaybe = id

validate
    :: (ADT (f Maybe) (f Identity), Constraints (f Maybe) (f Identity) IsMaybe)
    => f Maybe
    -> Maybe (f Identity)
validate = gtraverse @IsMaybe isMaybe