;;; CPSTAK -- A continuation-passing version of the TAK benchmark.
;;; A good test of first class procedures and tail recursion.
 
(define (cpstak x y z)

  (define (tak x y z k)
    (if (not (< y x))
        (k z)
        (tak (- x 1)
             y
             z
             (lambda (v1)
               (tak (- y 1)
                    z
                    x
                    (lambda (v2)
                      (tak (- z 1)
                           x
                           y
                           (lambda (v3)
                             (tak v1 v2 v3 k)))))))))

  (tak x y z (lambda (a) a)))

(define (main . args)
  (run-benchmark
    "cpstak"
    cpstak-iters
    (lambda (result) (equal? result 7))
    (lambda (x y z) (lambda () (cpstak x y z)))
    18
    12
    6))