From: Lennart Borgman <lennart.borgman@gmail.com>
To: Daniel Colascione <daniel@censorshipresearch.org>
Cc: Emacs development discussions <emacs-devel@gnu.org>
Subject: Re: O(N^2) behavior in LOOP
Date: Sun, 30 May 2010 00:14:44 +0200 [thread overview]
Message-ID: <AANLkTin2ADhO-yUJyhQDB90yMdz0ZCoKCsNsHBecBbC0@mail.gmail.com> (raw)
In-Reply-To: <4C018FD3.1020305@censorshipresearch.org>
On Sun, May 30, 2010 at 12:06 AM, Daniel Colascione
<daniel@censorshipresearch.org> wrote:
> On 5/29/10 5:56 PM, Daniel Colascione wrote:
>> Before I go fix the loop macro, is there a _reason_ for the nconc silliness?
>
> Err, never mind. LOOP has to work that way. An 'into' variable is
> visible; code that LOOP knows nothing about can modify it in arbitrary
> ways, which would invalidate any cached tail pointer, ruling out that
> approach. Also, code that inspects the variable should see a
> representation "as it should be", which rules out a temporarily-reversed
> representation, ruling out the push and nconc used in the
> anonymous-variable case.
>
> I don't see any way to do better than what LOOP does now without some
Perhaps advice against using it and give alternatives?
next prev parent reply other threads:[~2010-05-29 22:14 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-29 21:56 O(N^2) behavior in LOOP Daniel Colascione
2010-05-29 22:06 ` Daniel Colascione
2010-05-29 22:14 ` Lennart Borgman [this message]
2010-05-29 22:35 ` Geoff Gole
2010-05-29 23:58 ` [PATCH] use tail pointer for LOOP (Was: Re: O(N^2) behavior in LOOP) Daniel Colascione
2010-05-30 0:45 ` Ken Raeburn
2010-05-30 0:49 ` Daniel Colascione
2010-06-16 17:44 ` tomas
2010-06-16 18:10 ` [PATCH] use tail pointer for LOOP David Kastrup
2010-06-17 5:10 ` tomas
2010-06-17 7:18 ` Thien-Thi Nguyen
2010-06-17 9:22 ` tomas
2010-06-17 10:03 ` Thien-Thi Nguyen
2010-06-17 14:05 ` tomas
2010-06-17 15:16 ` Thien-Thi Nguyen
2010-06-17 10:12 ` Thien-Thi Nguyen
2010-06-17 20:48 ` Stefan Monnier
2010-06-18 7:07 ` David Kastrup
2010-06-18 13:40 ` Stefan Monnier
2010-05-30 17:05 ` Štěpán Němec
2010-05-30 17:09 ` Daniel Colascione
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