divisors   xtlang

(bind-func divisors
  "find the prime factors of n"
  (lambda (n)
    (letz ((factors (list))
           (d 2))
      (if (< n 2)
          (begin (set! factors (cons n factors))
                 void)
          (while (< d n)
            (if (= (% n d) 0)
                (begin (set! factors (cons d factors))
                       (set! n (/ n d)))
                (if (= d 2)
                    (set! d 3)
                    (set! d (+ d 2))))))
      factors)))