GNU bug report logs - #7174
23.2; `last' can be made faster by using `length'

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Package: emacs;

Reported by: IRIE Shinsuke <irieshinsuke <at> yahoo.co.jp>

Date: Fri, 8 Oct 2010 01:30:03 UTC

Severity: wishlist

Tags: patch

Found in version 23.2

Done: Glenn Morris <rgm <at> gnu.org>

Bug is archived. No further changes may be made.

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Message #48 received at 7174 <at> debbugs.gnu.org (full text, mbox):

From: IRIE Shinsuke <irieshinsuke <at> yahoo.co.jp>
To: Glenn Morris <rgm <at> gnu.org>
Cc: Juanma Barranquero <lekktu <at> gmail.com>,
	IRIE Shinsuke <irieshinsuke <at> yahoo.co.jp>, 7174 <at> debbugs.gnu.org
Subject: Re: bug#7174: 23.2; `last' can be made faster by using `length'
Date: Thu, 14 Oct 2010 13:35:41 +0900

At Wed, 13 Oct 2010 19:30:55 -0400,
Glenn Morris wrote:

> (I assume it is still faster than the original, BTW?)

I examined that.

The new `last' is still faster than the original even though it uses
`safe-length', except for particular cases as follows:

  (last nil 0)   (last '(foo) 0)   (last '(foo))

Here, '(foo) is a list of one element. In these cases, it's 2-5% slower.
If LIST has 1000 elements, 4-8 times faster.

IRIE Shinsuke
This bug report was last modified 14 years and 281 days ago.

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