{-# language TypeFamilies, UndecidableInstances #-}

data A = A
data B = B
data C = C

type family Test a where
    Test (A -> y) = B -> Test y
    Test (x -> y) = x -> Test y

g :: B -> A
g = undefined

class Test2 a b where
    test :: C -> a -> b
    
instance Test2 y y' => Test2 (A -> y) (B -> y') where
    test c f = test c (\b -> f (g b))

instance {-# OVERLAPPING #-} Test2 y y' => Test2 (x -> y) (x -> y') where
    test c f = (\x -> test c (f x))

main = undefined