From: David Kastrup <dak@gnu.org>
To: Mark H Weaver <mhw@netris.org>
Cc: 17147-done@debbugs.gnu.org
Subject: bug#17147: [PATCH] Add versions of and/or avoiding O(n^2) argument matching
Date: Thu, 05 Jun 2014 06:06:53 +0200 [thread overview]
Message-ID: <87vbsg57aa.fsf@fencepost.gnu.org> (raw)
In-Reply-To: <87lhtctb5o.fsf@yeeloong.lan> (Mark H. Weaver's message of "Wed, 04 Jun 2014 21:09:23 -0400")
Mark H Weaver <mhw@netris.org> writes:
> David Kastrup <dak@gnu.org> writes:
>
>> Fixes <http://bugs.gnu.org/17147>
>>
>> * module/ice-9/boot-9.scm (and, or): Add syntax rules that only do one
>> pattern matching operation per and/or rather than per argument.
>
> Thanks, but I ended up simply changing the macros to dotted tail
> patterns. It's commit 1ea8954814d124b995f2296bc6aec92adb566bc1.
Still one matching operation per argument (though an O(1) rather than an
O(n) one) rather than a single match.
Incidentally, most other syntax rules don't degrade on ... like that
because they do not do recursive matching on already matched patterns
either, case in point being the cond rule. So indeed and/or have been
about the worst culprits for this case.
--
David Kastrup
prev parent reply other threads:[~2014-06-05 4:06 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-31 9:58 bug#17147: Performance regression by 3000000% for evaluating "and" form David Kastrup
2014-03-31 22:30 ` Mark H Weaver
2014-03-31 23:21 ` David Kastrup
2014-04-01 2:55 ` Mark H Weaver
2014-04-01 6:17 ` David Kastrup
2014-04-01 7:10 ` Mark H Weaver
2014-04-01 8:22 ` David Kastrup
2014-04-01 11:59 ` David Kastrup
2014-04-01 16:19 ` Mark H Weaver
2014-05-12 6:08 ` bug#17147: Another idea David Kastrup
2014-05-13 13:03 ` bug#17147: Scalability front and back David Kastrup
2014-06-04 14:18 ` bug#17147: [PATCH] Add versions of and/or avoiding O(n^2) argument matching David Kastrup
2014-06-05 1:09 ` Mark H Weaver
2014-06-05 4:06 ` David Kastrup [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/guile/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87vbsg57aa.fsf@fencepost.gnu.org \
--to=dak@gnu.org \
--cc=17147-done@debbugs.gnu.org \
--cc=mhw@netris.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).