From: rm@fabula.de
Cc: "Lars J. Aas" <larsa@sim.no>, Keith Wright <kwright@gis.net>,
mvo@zagadka.ping.de, guile-user@gnu.org
Subject: Re: defining new character names?
Date: Wed, 21 Aug 2002 11:54:22 +0200 [thread overview]
Message-ID: <20020821095422.GC23971@www> (raw)
In-Reply-To: <uw565y4lhlx.fsf@saturn.math.uni-magdeburg.de>
On Wed, Aug 21, 2002 at 10:51:38AM +0200, Matthias Koeppe wrote:
[...]
>
> It would break everything.
I agree with that (see previous post)
[...]
> As I wrote before, I believe you are misunderstanding the role of the
> #\ read syntax. It is not meant as a syntax for character constants;
> rather it is a way to specify literal characters, like
>
> #\c
Hmm, what's the difference between 'character constant' and 'literal characters'
for you? The way i understand the '#\...' read extension, it also provides a
mean to ease writing hard-to-write/read character constants (like tab,
space, dc1, page, null etc.). Since it's really hard to read the following
code:
(if (eq? the-char #\
) (display 'yes))
there is the convenience of writing:
(if (eq? the-char #\newline) (display 'yes))
Now, the notion of 'hard to read/write' character is different for different
users (not _only_ vim users, french/german accented characters can be tricky
too :), so why not extend guiles read options to tailor the set of "named"
characters to the users needs?
> There is also no special syntax for string constants, or integer
> constants in Guile; there only is read syntax for literal strings, like
Are you focusing on the 'constant'-ness?
> "Error"
_is_ constant, afaik.
and so is 314159265
> and literal numbers,
>
> 314159265.
>
> If you want to create a named constant, you simply do
>
> (define error-message "Error")
> (define scaled-pi 314159265)
No. 'error-message' is not constant after that:
(set! error-message 'moep?)
> In the same way, you do
>
> (define paren-close-char #\051)
>
> or
>
> (define paren-close-char (integer->char 41))
>
> What I think _would_ be useful for Guile is a new DEFINE form that
> creates constant variables, like DEFINE-CONSTANT, so you could say
>
> (define-constant paren-close-char (integer->char 41)).
>
> This may serve useful for compiler optimizations, because the compiler
> (if any) could assume that the value of the variable never changes.
Yes, but that's an enirely different topic ....
Ralf
> Regards,
>
> --
> Matthias K?ppe -- http://www.math.uni-magdeburg.de/~mkoeppe
>
>
> _______________________________________________
> Guile-user mailing list
> Guile-user@gnu.org
> http://mail.gnu.org/mailman/listinfo/guile-user
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next prev parent reply other threads:[~2002-08-21 9:54 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-08-19 10:07 defining new character names? Lars J. Aas
2002-08-19 23:36 ` Marius Vollmer
2002-08-20 3:40 ` Keith Wright
2002-08-21 4:01 ` Keith Wright
2002-08-21 8:12 ` Lars J. Aas
2002-08-21 8:43 ` rm
2002-08-21 8:51 ` Matthias Koeppe
2002-08-21 9:17 ` Lars J. Aas
2002-08-21 9:54 ` rm [this message]
2002-08-27 15:09 ` Matthias Koeppe
2002-09-01 16:24 ` Rob Browning
2002-09-01 16:49 ` Marius Vollmer
2002-08-20 8:20 ` Matthias Koeppe
2002-08-20 10:18 ` rm
2002-08-21 9:20 ` Matthias Koeppe
2002-08-21 10:00 ` rm
2002-08-21 18:01 ` Marius Vollmer
-- strict thread matches above, loose matches on Subject: below --
2002-08-21 15:24 Lynn Winebarger
2002-08-21 17:33 ` Keith Wright
2002-08-21 18:27 ` Lynn Winebarger
2002-08-21 19:06 ` rm
2002-08-21 19:47 ` Lynn Winebarger
2002-08-21 23:04 ` Keith Wright
2002-08-21 23:07 ` Keith Wright
2002-08-21 19:40 ` Marius Vollmer
2002-08-22 4:12 ` Keith Wright
2002-08-22 5:16 ` Lynn Winebarger
2002-08-22 7:42 ` rm
2002-08-22 8:39 ` Lynn Winebarger
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