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[Caml-list] Ocaml interface to ctype.h functions
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Date: -- (:)
From: Shawn Wagner <shawnw@s...>
Subject: Re: [Caml-list] Ocaml interface to ctype.h functions
On Tue, Jun 05, 2001 at 06:29:09PM +0200, Xavier Leroy wrote:
> > I've been working on some projects recently where it would be nice to have
> > access to the ctype.h character classification functions (isalpha(),
> > isspace(), etc.) in Ocaml, and couldn't find anything like them in a search
> > through the standard library. It's easy to whip up a library for this, but
> > before doing so, I thought I'd ask if there's any plans to put them in the
> > Character module or some other place it makes sense to have them.
> 
> It would make sense to have classification functions in the Char
> module.  The main issue is: what is a letter?, or: how to deal with
> character sets.
> 
> If only one, fixed character set is supported (e.g. US-ASCII or
> Latin-1), it's truly easy, but will not satisfy everyone.  OCaml has
> already been criticized for supporting ISO Latin-1 accented letters in
> identifiers!  (Look at the caml-list archives if you don't believe me.)
> 
> Building on the C functions isalpha(), etc, is a bit of a cop-out,
> because then we're dependent on what these functions actually do on a
> variety of Unix, Windows and Macintosh systems.  In particular, we
> become dependent on the ISO C internationalization framework ("locales"),
> which I think is a mess because it relies too much on a global state
> (the current locale).

Okay, I've done the isFOO() and setlocale() interface as a seperate library
for now, and will release it soon (Like, tonight). Am I correct in assuming
that it's not likely to make it into the standard library based on the
above, though?

I've discovered that setlocale() of LC_CTYPE is done already by the runtime,
by a function used in Char.escaped... so if locales are a mess, they're a
mess ocaml is already stuck with.  Also, someone else is asking about a way
to set LC_NUMERIC from in ocaml, so I'm not alone in having a need for
setlocale, at least.


> 
> To give an example of the kind of problems I fear, just doing
> setlocale(LC_ALL, "fr_FR") in an OCaml program causes
> float_of_string "3.14" to return 0.0.  Guess why?  float_of_string
> relies on the C function atof(), which is internationalized, and
> doesn't recognize "." as a decimal point -- French uses a "," instead...

This is why LC_ALL is bad, and why it's better to just use the specific
locale categories you want.


-- 
Shawn Wagner
shawnw@speakeasy.org
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