;; RECURSIVE LAMBDA
;; ================
(assert= 720 ((-> (n)
    (if (= n 0) 1
    (* n (self (- n 1))))) 6))

;; RECURSIVE NAMED LAMBDA
;; ======================
($ fac (-> (n)
   (if (= n 0) 1
       (* n (fac (- n 1))))))

(assert= 120 (fac 5))