data IntList = { Nil, Cons(Int, IntList) }

defn ones = { Cons 1 ones }
defn zipSum l r = {
    case l of {
        Nil -> { 0 }
        Cons(lv, lt) -> {
            case r of {
                Nil -> { 0 }
                Cons(rv, rt) -> {
                    (lv + rv) + zipSum lt rt
                }
            }
        }
    }
}
defn main = { zipSum (Cons 0 (Cons 1 Nil)) ones }