From: Stefan Monnier <monnier@iro.umontreal.ca>
To: help-gnu-emacs@gnu.org
Subject: Re: cl-dolist, dolist, cl-return,
Date: Wed, 08 Jul 2015 10:44:13 -0400 [thread overview]
Message-ID: <jwvvbdur9rk.fsf-monnier+gmane.emacs.help@gnu.org> (raw)
In-Reply-To: 87k2ub2bgb.fsf@nl106-137-147.student.uu.se
>> Right, the question often makes sense for loop boundary computations,
>> but for this specific case, if you think enough about it, it makes no
>> sense to re-evaluate it: you'd have to use an index into the list,
>> and at each iteration, increment the index, recompute the list, and
>> do an (nth <index> <list>), which would overall be
>> *really* inefficient.
> No, of course I don't want to re-evaluate it! I didn't
My point was that the re-evaluation part would be just a side-problem:
even if your expression is a mere variable (so re-evaluating it is very
cheap), the need to use `nth' at each step would force an O(N^2)
complexity to this loop.
Stefan
next prev parent reply other threads:[~2015-07-08 14:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-08 0:14 cl-dolist, dolist, cl-return, Emanuel Berg
2015-07-08 0:31 ` John Mastro
2015-07-08 3:09 ` Stefan Monnier
2015-07-08 10:25 ` Emanuel Berg
2015-07-08 14:44 ` Stefan Monnier [this message]
2015-07-08 23:19 ` Emanuel Berg
2015-07-09 1:49 ` John Mastro
2015-07-09 22:00 ` Emanuel Berg
[not found] ` <mailman.6636.1436479362.904.help-gnu-emacs@gnu.org>
2015-07-10 18:44 ` Barry Margolin
2015-07-11 18:52 ` Emanuel Berg
2015-07-10 16:57 ` Stefan Monnier
2015-07-08 10:23 ` Emanuel Berg
[not found] <mailman.6511.1436314595.904.help-gnu-emacs@gnu.org>
2015-07-08 3:25 ` Pascal J. Bourguignon
2015-07-08 10:17 ` Emanuel Berg
2015-07-08 14:02 ` Drew Adams
2015-07-08 23:10 ` Emanuel Berg
[not found] ` <mailman.6588.1436397019.904.help-gnu-emacs@gnu.org>
2015-07-08 23:56 ` Pascal J. Bourguignon
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