(define run-time
  (lambda (f n)
    (define runtime
      (lambda ()
        (/ (- (current-process-milliseconds)
              (current-gc-milliseconds))
           1000.)))
    (define loop
      (lambda (count start-time)
        (let ((value (f n)))
          (let ((cur-time (runtime)))
            (cond ((> cur-time (+ 1 start-time))
                   (newline)
                   (display ";Time: ")
                   (display (/ (- cur-time start-time) count))
                   (newline)
                   value)
                  (else
                   (loop (+ count 1) start-time)))))))
    (loop 1 (runtime))))
(define time run-time)