From: "Pascal J. Bourguignon" <pjb@informatimago.com>
To: help-gnu-emacs@gnu.org
Subject: Re: execute defun on reception of signal
Date: Tue, 14 Jul 2015 04:41:40 +0200 [thread overview]
Message-ID: <87bnffo3yz.fsf@kuiper.lan.informatimago.com> (raw)
In-Reply-To: mailman.6892.1436840915.904.help-gnu-emacs@gnu.org
Emanuel Berg <embe8573@student.uu.se> writes:
> Rusi <rustompmody@gmail.com> writes:
>
>> However on a docs-improving note here's this little
>> titbit: [On other thread] There was this claim
>> "letrec is nice" or some such. Since I know letrec
>> from scheme etc but never seen in elisp I was
>> curious. I find: describe-function tells nothing
>> about the recursion the elisp info pages (index)
>> seems to not have it at all
>
> There is no mention of "letrec" in
>
> /usr/share/info/emacs-24/elisp.info
>
> I don't know the policy. Are *all* functions, macros,
> etc. supposed to be in the Elisp manual?
letrec is not emacs lisp, it's scheme.
In Common Lisp, one would use labels, so in emacs lisp you can write:
(require 'cl)
(defun fact (n)
(labels ((f (n f)
(if (plusp n)
(f (- n 1) (* n f))
f)))
(f n 1)))
provides a nice tail-recursive factorial implementation.
(fact 10) --> 3628800
(fact 41) --> 1716706262231547904
--
__Pascal Bourguignon__ http://www.informatimago.com/
“The factory of the future will have only two employees, a man and a
dog. The man will be there to feed the dog. The dog will be there to
keep the man from touching the equipment.” -- Carl Bass CEO Autodesk
next prev parent reply other threads:[~2015-07-14 2:41 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-12 1:59 execute defun on reception of signal Emanuel Berg
2015-07-12 10:27 ` Andy Moreton
2015-07-12 16:56 ` Emanuel Berg
2015-07-12 18:54 ` Andy Moreton
2015-07-13 3:53 ` Vaidheeswaran C
2015-07-14 1:49 ` Emanuel Berg
[not found] ` <mailman.6808.1436727285.904.help-gnu-emacs@gnu.org>
2015-07-13 2:29 ` Rusi
2015-07-13 2:57 ` Emanuel Berg
2015-07-13 3:39 ` Vaidheeswaran C
2015-07-14 1:43 ` Emanuel Berg
2015-07-14 1:58 ` Vaidheeswaran C
2015-07-14 1:59 ` Emanuel Berg
2015-07-14 2:07 ` Emanuel Berg
2015-07-14 2:09 ` Vaidheeswaran C
2015-07-14 22:14 ` Emanuel Berg
2015-07-13 8:28 ` Andy Moreton
2015-07-13 14:49 ` Nicolas Richard
2015-07-13 15:22 ` Eli Zaretskii
2015-07-13 14:44 ` Eli Zaretskii
[not found] ` <mailman.6850.1436798656.904.help-gnu-emacs@gnu.org>
2015-07-13 14:57 ` Rusi
2015-07-13 15:18 ` Thierry Volpiatto
2015-07-13 15:28 ` Eli Zaretskii
[not found] ` <mailman.6858.1436801328.904.help-gnu-emacs@gnu.org>
2015-07-13 16:13 ` Rusi
2015-07-14 1:53 ` Emanuel Berg
[not found] ` <mailman.6892.1436840915.904.help-gnu-emacs@gnu.org>
2015-07-14 2:41 ` Pascal J. Bourguignon [this message]
2015-07-14 21:33 ` Emanuel Berg
[not found] ` <mailman.6932.1436909731.904.help-gnu-emacs@gnu.org>
2015-07-14 22:11 ` Pascal J. Bourguignon
2015-07-14 22:21 ` Emanuel Berg
[not found] ` <mailman.6936.1436912565.904.help-gnu-emacs@gnu.org>
2015-07-15 15:25 ` Rusi
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