On Mon, 22 Feb 2016 13:01:01 +0100
address@hidden (Ludovic Courtès) wrote:
> Chris Vine <address@hidden> skribis:
>
> > It features an a-sync procedure (in coroutines.scm) which can be
> > used to provide await semantics on asynchronous code (so as to
> > remedy inversion of control), and will work with callbacks for any
> > event loop, including the glib event loop wrapped by guile-gnome.
> > More to the point, it also provides a thread safe event loop for
> > guile (event-loop.scm) with support for watches on ports/file
> > descriptors, and now supports proper timeouts, and permits events
> > to be posted by other tasks. This includes tasks running on other
> > threads, for which there is a helper procedure
> > a-sync-run-task-in-thread.
>
> Interesting. Have you tried to integrate it with one of the
> object-oriented event loops like in GLib? (Back in the day I thinking
> about something like that to avoid the callback hell in Guile-Avahi.)
>
> Thanks for the tasty dish! :-)
>
> Ludo’.
This is an example of how you might use a-sync with guile-gnome:
;;;;;;;;
(use-modules (gnome glib) (coroutines))
(define main-loop (g-main-loop-new #f #f))
(a-sync (lambda (await resume)
;; launch asynchronous task
(g-idle-add (lambda ()
(display "In first async callback\n")
(resume "Hello via async\n")
#f))
(display "About to make first wait\n")
(display (string-append "Back in waitable procedure, and the callback says: " (await)))
;; launch another asynchronous task
(g-idle-add (lambda ()
(display "In second async callback\n")
(g-main-loop-quit main-loop)
(resume)
#f))
(display "About to make second wait\n")
(await)
(display "Quitting\n")))
(display "Starting main loop\n")
(g-main-loop-run main-loop)
;;;;;;;;
It's very different from asyncio's await. The kind of coroutine you use are more general than Python's coroutine.
Basically await procedure takes another procedure that implement the resume behavior. In a sens `(await idle)` is similar to some kind of `(await sleep 5)` implementation. Not sure this last sentence make really sens to you.
Happy hacking!