From: Francis Moreau <francis.moro@gmail.com>
To: help-gnu-emacs@gnu.org
Subject: Re: Basic questions about elisp
Date: Mon, 09 Nov 2009 21:51:18 +0100 [thread overview]
Message-ID: <m2ocnbo20p.fsf@gmail.com> (raw)
In-Reply-To: mailman.10266.1257674088.2239.help-gnu-emacs@gnu.org
tomas@tuxteam.de writes:
> On Sat, Nov 07, 2009 at 06:49:52AM -0800, Francis Moreau wrote:
>> On 6 nov, 22:18, p...@informatimago.com (Pascal J. Bourguignon) wrote:
>> > Francis Moreau <francis.m...@gmail.com> writes:
>
> [...]
>
>> > > Actually the same stands for the implementation of the list, where
>> > > nconc, length... are O(n). I wouldn't have thought that lists are really
>> > > implemented by the car & cdr thing only.
>> >
>> > Why not? If people have been repeating for 50 years that lisp lists
>> > are implemented with cons, car and cdr...
>>
>> Because I can understand there were some memory constraints 50 years
>> ago that force lisp lists to be as small as possible. But I would have
>> thought lisp lists (or (e)lisp) to evolve as computer memories did.
>
> There's no "one data structure fits all" philosophy here. Use list for
> "list things" and arrays for "array things". Nowadays all Lisps have
> some form or other of array.
>
> And still, lists are among the strongest points of Lisp. They are
> simple and flexible, they are the representation of Lisp programs. They
> are the reason why Lisp programmers are writing programs that write
> programs ever since ~50 years ago.
>
> If a list doesn't fit your bill, by all means: use defstruct, use
> arrays, use hashes. But (as Pascal pointed out), sometimes lists fit a
> bill quite unexpectedly, if you are willing to think flexibly (e.g. push
> new elements at the head instead of append, etc).
yeah, optimized push/pop operations of lists is a bit unusual for me,
it's actually like using stack instead of lists. Specially since the
first code I tried to write with elisp was a sort algo where order
matters and first parsed elements need to be the first ones in the list.
Thanks
--
Francis
next prev parent reply other threads:[~2009-11-09 20:51 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-05 11:13 Basic questions about elisp Francis Moreau
2009-11-05 11:50 ` Lennart Borgman
[not found] ` <mailman.10118.1257421858.2239.help-gnu-emacs@gnu.org>
2009-11-05 12:07 ` Francis Moreau
2009-11-05 12:44 ` Lennart Borgman
2009-11-05 12:59 ` David Kastrup
2009-11-05 14:25 ` Francis Moreau
2009-11-05 14:37 ` Pascal J. Bourguignon
2009-11-05 14:58 ` Pascal J. Bourguignon
2009-11-05 12:57 ` tomas
[not found] ` <mailman.10122.1257425638.2239.help-gnu-emacs@gnu.org>
2009-11-05 14:29 ` Francis Moreau
2009-11-05 14:41 ` Pascal J. Bourguignon
2009-11-05 15:06 ` David Kastrup
2009-11-06 16:03 ` Francis Moreau
2009-11-06 16:49 ` David Kastrup
2009-11-06 20:53 ` Francis Moreau
2009-11-06 21:18 ` Pascal J. Bourguignon
2009-11-07 14:49 ` Francis Moreau
2009-11-07 17:50 ` Pascal J. Bourguignon
2009-11-08 9:46 ` tomas
[not found] ` <mailman.10266.1257674088.2239.help-gnu-emacs@gnu.org>
2009-11-09 20:51 ` Francis Moreau [this message]
2009-11-08 15:18 ` Francis Moreau
2009-11-08 16:58 ` tomas
2009-11-08 17:12 ` Pascal J. Bourguignon
2009-11-09 21:04 ` Francis Moreau
2009-11-10 12:11 ` Joost Kremers
2009-11-10 14:16 ` Francis Moreau
2009-11-10 18:53 ` David Kastrup
2009-11-06 5:06 ` Barry Margolin
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