An example of the synchronous channels in Racket

channel-example.rkt

#lang racket

;; A translation of http://tour.golang.org/#63 in Racket

(define (sum elts c)
  (channel-put c (for/sum ([e elts]) e)))


(define (main)
  (define a (list 7 2 8 -9 4 0))
  (define c (make-channel))
  (thread (lambda () (sum (take a (quotient (length a) 2)) c)))
  (thread (lambda () (sum (drop a (quotient (length a) 2)) c)))
  (define-values (x y) (values (channel-get c) (channel-get c)))
  (displayln x)
  (displayln y)
  (displayln (+ x y)))

(main)