(let (y f = let (g x u = f (x x) u) in g g)
in

(let (map f = y $ \ map xs ->
                     case xs of
                       (Cons x xs -> Cons (f x) (map xs))
                       (Nil       -> Nil))

     (mul = y $ \ rec a b ->
                 case b of
                   (0 -> 0)
                   (n -> add a $ rec a $ add b $ negate 1))
in

(let (factorial = y $ \ rec a ->
                       case a of
                         (0 -> 1)
                         (a  -> mul a $ rec $ add a $ negate 1))
in

 --map ( \ x -> add 1 x ) (Cons 1 $ Cons 2 Nil) )))
 factorial 7)))