(let (
    [fix (lam (f)
        (let ([t (lam (x) (f (lam (v) (x x v))))])
            (t t)))]
    [printn [fix (lam (recur n)
        (((<= n 0)
            (lam () 0)
            (lam () (recur (- (debug n) 1))))))]]
) (printn 13))