gistfile1.rkt

#lang racket
(define-syntax custodian-protect
  (syntax-rules ()
    ((custodian-protect main-body ...)
     (let ((protection #f)
           (original #f))
       (dynamic-wind (lambda ()
                       (set! original (current-custodian))
                       (set! protection (make-custodian original))
                       (current-custodian protection))
                     (lambda () main-body ...)
                     (lambda ()
                       (custodian-shutdown-all protection)
                       (current-custodian original)))))))



(define kont
  (custodian-protect
   (call/cc (lambda (k)
              (thread (lambda () ((lambda (x) (begin (printf "Hey there")(x x)))
                                  (lambda (x) (begin (printf "Hey there") (sleep 1)(x x))))))
              (custodian-protect
               (define x (open-input-file "/tmp/foo"))
               (define
                 port
                 (call/cc (lambda (k2)
                            (k (list k2 x)))))
               (display (read port)))
              (sleep 5)(k #f)))))

(define kontinuation (first kont))
(define port (second kont))

(kontinuation port)