Cooperative threading with generators

threading.el

;; Practical cooperative threading in emacs 25 using generators.
;; Requires generator.el library of emacs 25 (can be used stand-alone
;; on anything 24.3+)

;; Eval the next three forms.  To start the computation, run the
;; timer.
(fset 'foo
      (iter-lambda ()
        (let ((i 0))
          ;; limit to 3 interupts for demo purposes
          (while (<= i 3)
            ;; Send any event to emacs (hit a key combo) to interupt
            ;; the work being done.  The work should be in granular
            ;; enough chunks to quickly terminate and not block the
            ;; event loop for long.
            (while (not (input-pending-p))
              ;; Do work here.  Open the messages buffer and see how
              ;; it accumulates nicely :)
              (message "foo"))
            (iter-yield (incf i))))))

(setq my-iterator (foo))

(defun my-job ()
  (iter-next my-iterator)
  (run-with-idle-timer 0 nil 'my-job))

;; then eval this
(run-with-idle-timer 0 nil 'my-job)