More complex green-threads / async example.

async2.lisp

(ql:quickload "green-threads")
(ql:quickload "cl-async")

(defun f-http-client (url &rest rest)
  (let ((http-future (green-threads:make-future)))
    (apply #'cl-async:http-client
           url
           #'(lambda (status headers body)
               (green-threads:complete-future 
                 http-future status headers body nil))
           #'(lambda (err)
               (green-threads:complete-future
                 http-future nil nil nil err))
           rest)
    http-future))

(defun f-delay (&key time)
  (let ((delay-future (green-threads:make-future)))
    (funcall #'cl-async:delay
           #'(lambda ()
               (green-threads:complete-future 
                 delay-future))
           :time time)
    delay-future))

(cl-async:start-event-loop
  (lambda ()
    ;; The trick to having green threads run together is to call them from green thread
    (green-threads:with-green-thread
      ;; Delay thread
      (green-threads:with-green-thread
        (format t "Starting 3 second delay.~%")
        (green-threads:wait-on (f-delay :time 3.0))
        (format t "Finished 3 second delay.~%"))
      ;; HTTP request thread
      (green-threads:with-green-thread
        (format t "Starting HTTP request.~%")
        (green-threads:wait-on (f-http-client "http://blog.thezerobit.com/" :timeout 5))
        (format t "Finished HTTP request.~%")) 
      ;; Do some other things thread
      (green-threads:with-green-thread
        (format t "Doing other things in third thread...~%"))
      )))

;; output:
;; Starting 3 second delay.
;; Starting HTTP request.
;; Doing other things in third thread...
;; Finished HTTP request.
;; Finished 3 second delay.