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From: Stefan Monnier <monnier@iro.umontreal.ca>
To: help-gnu-emacs@gnu.org
Subject: Re: no empty (zero) string predicate in Elisp
Date: Sun, 26 Apr 2015 17:25:47 -0400	[thread overview]
Message-ID: <jwvtww2a8sq.fsf-monnier+gmane.emacs.help@gnu.org> (raw)
In-Reply-To: 87wq0zild3.fsf@kuiper.lan.informatimago.com

> This is exactly what I'm pointing to!  If you want to consider how elisp
> intgers are encoded on the native machine, then you definitely want a
> zerop function, because there are BEQ and SEQ instructions.

But that's not the case: Elisp is compiled to Emacs's byte-code
"machine" which does not have such instructions.

> Not in emacs-version "24.3.1"  where I produced the disassembly
> provided.  But I'm happy to see it being optimized, this is one more
> reason to keep it and use it.

Indeed, the inefficiency of zerop was pointed out "recently" and has
I think it's only fixed in Emacs-25.


        Stefan




  reply	other threads:[~2015-04-26 21:25 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-04-25  3:44 no empty (zero) string predicate in Elisp Emanuel Berg
2015-04-25  9:26 ` Nicolas Petton
2015-05-16  9:23   ` Nicolas Petton
2015-05-16 13:22     ` Bozhidar Batsov
2015-05-16 13:28       ` Bozhidar Batsov
2015-05-16 13:36         ` Bozhidar Batsov
2015-05-16 13:46           ` Eli Zaretskii
2015-05-16 13:43     ` Stefan Monnier
2015-05-16 15:27     ` Drew Adams
     [not found] ` <mailman.1583.1429954907.904.help-gnu-emacs@gnu.org>
2015-04-25 11:22   ` Emanuel Berg
2015-04-25 13:30 ` Stefan Monnier
     [not found] ` <mailman.1591.1429968677.904.help-gnu-emacs@gnu.org>
2015-04-25 14:48   ` Pascal J. Bourguignon
2015-04-26  2:52     ` Stefan Monnier
2015-04-27 10:28       ` zerop: compiler macro vs defsubst (was: no empty (zero) string predicate in Elisp) Nicolas Richard
2015-04-27 12:19         ` zerop: compiler macro vs defsubst Stefan Monnier
     [not found]     ` <mailman.1626.1430016741.904.help-gnu-emacs@gnu.org>
2015-04-26  4:06       ` no empty (zero) string predicate in Elisp Pascal J. Bourguignon
2015-04-26 21:25         ` Stefan Monnier [this message]
2015-04-26  4:26       ` Rusi
2015-04-26 12:36   ` Emanuel Berg
2015-04-26 15:03     ` Pascal J. Bourguignon
2015-04-26 18:34       ` Emanuel Berg
2015-04-26 18:59         ` Marcin Borkowski
     [not found]         ` <mailman.1658.1430074770.904.help-gnu-emacs@gnu.org>
2015-04-26 19:06           ` Emanuel Berg
2015-04-26 20:11             ` Marcin Borkowski
     [not found]             ` <mailman.1662.1430079142.904.help-gnu-emacs@gnu.org>
2015-04-27  1:00               ` Emanuel Berg
2015-04-26 17:28     ` Rusi
2015-04-26 18:39       ` Emanuel Berg

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