Re: async.el: A simple asynchronous framework for Emacs

[John Wiegley <jwiegley@gmail.com>]

Apropos of nothing, just discovered that `apply-partially' is a nice way to
run one-liners asynchronously:

  (async-start (apply-partially #'copy-file from to ok-flag preserve-time)
               (apply-partially #'message "Copy done: %s -> %s" from to))

The alternative is less consistent:

  (async-start `(lambda () (copy-file ,from ,to ,ok-flag ,preserve-time))
               (lambda () (message "Copy done: %s -> %s" from to)))

Since `form' and `to' need their values passed to the child process, while the
variables remain in scope for the callback (thanks to closures).  Of course,
the <24 version is equally consistent in its ugliness:

  (async-start `(lambda () (copy-file ,from ,to ,ok-flag ,preserve-time))
               `(lambda () (message "Copy done: %s -> %s" ,from ,to)))

John