simple (ice-9 occam-channel) echo example in guile

gistfile1.scm

(define-module (channels)
  #:use-module (ice-9 occam-channel)
  #:export (start-echo))

;;; use like this:
;;;  > (define c (start-echo))
;;;  > (! c 'test)
;;;  > (? c)
;;;  $1 = (echo test)
;;;  > (! c '(some more "input data"))
;;;  > (? c)
;;;  $2 = (echo (some more "input data"))
(define (start-echo)
  (let ((chan (make-channel)))
    (call-with-new-thread
      (lambda ()
        (let loop ()
          (let ((in (? chan)))
            (case in
              ((quit) #f)
              (else
               (! chan (list 'echo in))
               (loop)))))))
    chan))