data List = { Nil, Cons Int List }

defn sumZip l m = {
    case l of {
        Nil -> { 0 }
        Cons x xs -> {
            case m of {
                Nil -> { 0 }
                Cons y ys -> { x + y + sumZip xs ys }
            }
        }
    }
}

defn ones = { Cons 1 ones }

defn main = { sumZip ones (Cons 1 (Cons 2 (Cons 3 Nil))) }