From: pjb@informatimago.com (Pascal J. Bourguignon)
To: help-gnu-emacs@gnu.org
Subject: Re: What is the best way to navigate #ifdef and #endif in C program
Date: Fri, 06 Aug 2010 15:55:36 +0200 [thread overview]
Message-ID: <87vd7nvo9z.fsf@kuiper.lan.informatimago.com> (raw)
In-Reply-To: 27e5f238-760f-4fee-93ce-0b9ce04741e8@5g2000yqz.googlegroups.com
Elena <egarrulo@gmail.com> writes:
> On Aug 6, 10:43 am, Pascal Costanza <p...@p-cos.net> wrote:
>> Here is a way how to do TCO in Common Lisp:http://groups.google.com/group/comp.lang.lisp/msg/8f9dcf58a00aca27
>>
>> It can't be implemented as just a macro, because it requires the
>> cooperation of different parts of a program. You can only do that as a
>> "real" language extension.
>
> Thanks for the link, Pascal.
>
> IMHO, that would be a better way to make TCO available, that is: TCO
> should be explicit, since you know beforehand whether you want your
> function to be tail recursive or not. Then, whenever you fail to
> implement a tail recursion among mutually recursive functions, the
> compiler should complain. If I'm not mistaken, OCaml has (somewhat)
> explicit TCO. Or detecting such errors would better be left to test
> cases?
You're all forgetting something.
In Common Lisp, most tail calls ARE NOT tail calls.
This is because of dynamic binding. Not only of variables, but also
of unwind frames, a lot of them are hidden in with-* macros, catch
frames, condition handlers, restarts, etc.
So even if TCO was mandatory, it couldn't be applied often in Common
Lisp programs.
--
__Pascal Bourguignon__ http://www.informatimago.com/
next prev parent reply other threads:[~2010-08-06 13:55 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-03 0:31 What is the best way to navigate #ifdef and #endif in C program Daniel (Youngwhan)
2010-08-04 4:45 ` [OT] " Fren Zeee
2010-08-04 10:27 ` Pascal J. Bourguignon
2010-08-04 10:38 ` Alessio Stalla
2010-08-04 11:57 ` Pascal J. Bourguignon
2010-08-04 14:37 ` Elena
2010-08-04 14:59 ` Arzobispo Andante
2010-08-04 15:09 ` Peter Keller
2010-08-04 15:35 ` Peter Keller
2010-08-05 19:04 ` Elena
2010-08-05 21:10 ` Peter Keller
2010-08-05 23:46 ` Pascal J. Bourguignon
[not found] ` <8c27aoFij2U1@mid.individual.net>
2010-08-06 11:17 ` Elena
2010-08-06 13:55 ` Pascal J. Bourguignon [this message]
2010-08-04 16:20 ` Elena
2010-08-04 16:23 ` Elena
2010-08-05 18:00 ` Emmy Noether
2010-08-06 4:59 ` [OT] " Aaron W. Hsu
2010-08-05 17:30 ` Johan Bockgård
2010-08-06 17:03 ` Alan Mackenzie
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