0 :: a
add :: a → a → a
cons :: b → c → c
id :: a → a
map :: (b → b) → c → c
nil :: c
s :: a → a
id(X) → X
add(0) → id
add(s(Y), U) → s(add(Y, U))
map(H, nil) → nil
map(I, cons(P, X1)) → cons(I(P), map(I, X1))