source: project/demonstrations/continuations/suspensions.scm @ 21228

;;;; suspensions.scm


(use suspension utils)


(define (run halt)
  (do ((i 1 (add1 i)))
      ((>= i 10))
    (print i)
    (when (eq? i halt)
      (call/cc
       (lambda (k)
         (continuation-suspend
          (lambda (state)
            (print "saving state ...")
            (with-output-to-file "state"
              (cut display state))
            (exit))))))))

(let* ((args (command-line-arguments))
       (x (and (pair? args) (car args))))
  (print "start.")
  (with-limited-continuation
   (lambda ()
     (cond ((and x (string->number x)) => run)
           (x (continuation-resume (read-all x) #f))
           (else
            (print "please pass either a number or a filename.")))
     (print "end."))))