gistfile1.clj

; letfn is a Clojure macro that allows for mutually recursive functions.
; In some lisps, letfn (or letrec) will expand to a lambda expression.
(letfn [(fact-helper [total n]
          (if (<= n 1)
            total
            (fact-helper (* n total) (- n 1))))]
  (defn fact [n]
    (fact-helper 1 n)))

(fact 5)           ; 120
(fact-helper 1 5)  ; Error: Unbound reference