data Boolx = Minx | Plusx

data Natx a = Zx | Sx a | SSx (Natx a) Boolx

map1 :: Natx Int -> (Int -> Int) -> Natx Int

map1 x = \ f -> case x of

Zx -> Sx (f 0)

Sx n -> Sx (f n)

SSx a t -> map2 a t f

map2 :: Natx Int -> Boolx -> (Int -> Int) -> Natx Int

map2 x = \ w f -> case x of

Zx -> Zx

Sx n -> Sx (n + 1)

SSx a t -> if t == Minx then SSx a w else map1 a f