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From: Andy Wingo <wingo@pobox.com>
To: David Kastrup <dak@gnu.org>
Cc: guile-devel@gnu.org
Subject: Re: Guile: What's wrong with this?
Date: Wed, 04 Jan 2012 12:32:26 -0500	[thread overview]
Message-ID: <87r4zfqsph.fsf@pobox.com> (raw)
In-Reply-To: <87hb0bgzkt.fsf@fencepost.gnu.org> (David Kastrup's message of "Wed, 04 Jan 2012 18:14:10 +0100")

On Wed 04 Jan 2012 12:14, David Kastrup <dak@gnu.org> writes:

> Andy Wingo <wingo@pobox.com> writes:
>
>> We could add a compiler option to turn string literals into
>> (string-copy FOO).  Perhaps that's the thing to do.
>
> What for?  It would mean that a literal would not be eq? to itself, a
> nightmare for memoization purposes.

  (eq? "hello" "hello")

This expression may be true or false.  It will be true in some
circumstances and false in others, in all versions of Guile.

> And for what?  For making code with explicitly undefined behavior
> exhibit a particular behavior that is undesirable in general.

The Scheme reports and the Guile manual are both positive and negative
specification: they require the implementation to do certain things, and
they allow it to do certain others.  Eq? on literals is one of the
liberties afforded to the implementation, and with good reason.  Correct
programs don't assume anything about the identities (in the sense of
eq?) of literals.

Andy
-- 
http://wingolog.org/



  reply	other threads:[~2012-01-04 17:32 UTC|newest]

Thread overview: 117+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-03  4:08 What's wrong with this? Bruce Korb
2012-01-03 15:03 ` Mike Gran
2012-01-03 16:26   ` Guile: " Bruce Korb
2012-01-03 16:30     ` Mike Gran
2012-01-03 22:24     ` Ludovic Courtès
2012-01-03 23:15       ` Bruce Korb
2012-01-03 23:33         ` Ludovic Courtès
2012-01-04  0:55           ` Bruce Korb
2012-01-04  3:12             ` Noah Lavine
2012-01-04 17:37               ` bytevector -- was: " Bruce Korb
2012-01-04 21:17             ` Ludovic Courtès
2012-01-04 22:36               ` Bruce Korb
2012-01-05  0:01                 ` Ludovic Courtès
2012-01-05 18:36                   ` non-reproduction of initial issue -- was: " Bruce Korb
2012-01-05 18:50                     ` Mark H Weaver
2012-01-04 12:19         ` Ian Price
2012-01-04 17:16           ` Bruce Korb
2012-01-04 17:21             ` Andy Wingo
2012-01-04 17:39             ` David Kastrup
2012-01-04 21:52             ` Ian Price
2012-01-04 22:18               ` Bruce Korb
2012-01-04 23:22                 ` Mike Gran
2012-01-04 23:59                 ` Mark H Weaver
2012-01-05 17:22                   ` Bruce Korb
2012-01-05 18:13                     ` Mark H Weaver
2012-01-05 19:02                       ` Mark H Weaver
2012-01-05 20:24                     ` David Kastrup
2012-01-05 22:42                     ` Mark H Weaver
2012-01-06  1:02                       ` Mike Gran
2012-01-06  1:41                         ` Mark H Weaver
2012-01-06  2:38                           ` Noah Lavine
2012-01-06 13:37                           ` Mike Gran
2012-01-06 14:11                             ` David Kastrup
2012-01-06 18:13                             ` Mark H Weaver
2012-01-06 19:06                               ` Bruce Korb
2012-01-06 19:19                                 ` David Kastrup
2012-01-06 20:03                                   ` Mark H Weaver
2012-01-07 16:13                                 ` Mark H Weaver
2012-01-07 17:35                                   ` mutable interfaces - was: " Bruce Korb
2012-01-07 17:47                                     ` David Kastrup
2012-01-07 18:30                                     ` Mark H Weaver
2012-01-07 18:55                                       ` Mark H Weaver
2012-01-06 22:23                               ` Guile BUG: " Bruce Korb
2012-01-06 23:11                                 ` Mark H Weaver
2012-01-06 23:35                                   ` Andy Wingo
2012-01-06 23:41                                   ` Bruce Korb
2012-01-07 15:00                                     ` Mark H Weaver
2012-01-07 15:27                                       ` Bruce Korb
2012-01-07 16:38                                         ` Mark H Weaver
2012-01-07 17:39                                           ` Bruce Korb
2012-01-09 15:41                                             ` Mark H Weaver
2012-01-09 17:27                                               ` Bruce Korb
2012-01-09 18:32                                                 ` Andy Wingo
2012-01-09 19:48                                                   ` Bruce Korb
2012-01-07 15:47                                       ` David Kastrup
2012-01-07 17:07                                         ` Mark H Weaver
2012-01-07 14:35                                   ` Mark H Weaver
2012-01-07 15:20                                     ` Mike Gran
2012-01-07 22:25                                     ` Ludovic Courtès
2012-01-10  9:13                                     ` The empty string and other empty strings Ludovic Courtès
2012-01-10 11:28                                       ` Mike Gran
2012-01-10 13:03                                         ` Mark H Weaver
2012-01-10 13:09                                           ` Mike Gran
2012-01-10 15:41                                           ` Mark H Weaver
2012-01-10 15:48                                             ` David Kastrup
2012-01-10 16:15                                               ` Mark H Weaver
2012-01-12 22:33                                                 ` Ludovic Courtès
2012-01-13  9:27                                                   ` David Kastrup
2012-01-13 16:39                                                     ` Mark H Weaver
2012-01-13 17:36                                                       ` David Kastrup
2012-01-16  8:26                                                       ` Marijn
2012-01-16  8:47                                                         ` David Kastrup
2012-01-20 21:31                                                       ` Andy Wingo
2012-01-10 14:10                                         ` David Kastrup
2012-01-10 12:21                                       ` Mike Gran
2012-01-10 12:27                                       ` Mark H Weaver
2012-01-10 16:34                                         ` Ludovic Courtès
2012-01-10 17:04                                           ` David Kastrup
2012-01-06 23:28                                 ` Guile BUG: What's wrong with this? Bruce Korb
2012-01-07 20:57                           ` Guile: " Ian Price
2012-01-08  5:05                             ` Mark H Weaver
2012-01-06  9:23                         ` David Kastrup
2012-01-05  7:22                 ` David Kastrup
2012-01-04 22:46             ` Ludovic Courtès
2012-01-04  3:04       ` Mike Gran
2012-01-04  9:35         ` nalaginrut
2012-01-04  9:41         ` David Kastrup
2012-01-04 21:07         ` Ludovic Courtès
2012-01-04 10:03     ` Mark H Weaver
2012-01-04 14:29       ` Mike Gran
2012-01-04 14:45         ` David Kastrup
2012-01-04 16:47         ` Andy Wingo
2012-01-04 17:14           ` David Kastrup
2012-01-04 17:32             ` Andy Wingo [this message]
2012-01-04 17:49               ` David Kastrup
2012-01-04 18:09                 ` Andy Wingo
2012-01-04 17:30           ` Bruce Korb
2012-01-04 17:44             ` David Kastrup
2012-01-04 18:26             ` Ian Price
2012-01-04 18:48               ` Mark H Weaver
2012-01-04 19:29               ` Bruce Korb
2012-01-04 20:20                 ` David Kastrup
2012-01-04 23:19                 ` Mark H Weaver
2012-01-04 23:28                   ` Bruce Korb
2012-01-07 15:43                   ` Fixed string corruption bugs (was Guile: What's wrong with this?) Mark H Weaver
2012-01-07 16:19                     ` Fixed string corruption bugs Andy Wingo
2012-01-04 18:31           ` Guile: What's wrong with this? Mark H Weaver
2012-01-04 18:43             ` Andy Wingo
2012-01-04 19:29               ` Mark H Weaver
2012-01-04 19:43                 ` Andy Wingo
2012-01-04 20:08                   ` Bruce Korb
2012-01-04 20:14                     ` David Kastrup
2012-01-04 20:56                     ` Andy Wingo
2012-01-04 21:30                       ` Bruce Korb
2012-01-04 17:19         ` Mark H Weaver
2012-01-05  4:24           ` Mark H Weaver
2012-01-04 22:37       ` Ludovic Courtès

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