nil :: intlist
cons :: Int -> intlist -> intlist

init :: (Int -> Int) -> intlist -> intlist
init(F) -> map([+](fsum(F,10)))

map :: (Int -> Int) -> intlist -> intlist
map(F, nil) -> nil
map(F, cons(H, T)) -> cons(F(H), map(F, T))

private fsum :: (Int -> Int) -> Int -> Int
fsum(F, 0) -> 0
fsum(F, N) -> F(N) + fsum(F, N-1) | N != 0