blog-static/code/compiler/08/examples/works3.txt

data List = { Nil, Cons Int List }
defn length l = {
    case l of {
        Nil -> { 0 }
        Cons x xs -> { 1 + length xs }
    }
}
defn main = { length (Cons 1 (Cons 2 (Cons 3 Nil))) }