doc rx regexps

doc rx regexps

[Kevin Ryde]

Is the Rx regexp library supported in the guile core any more?  I
can't see it, and I think the docs for that stuff in the manual should
be removed to stop anyone getting confused between those functions and
the posix regex functions.


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Re: doc rx regexps

[Marius Vollmer]

Kevin Ryde <user42@zip.com.au> writes:

> Is the Rx regexp library supported in the guile core any more?  I
> can't see it, and I think the docs for that stuff in the manual should
> be removed to stop anyone getting confused between those functions and
> the posix regex functions.

Ok.

-- 
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Re: doc rx regexps

[Julian Graham]

Yeah, I noticed this too, while I was looking for a lexer tool for
Guile and came across the old (lang lex) module.  (lang lex) is pretty
straightforward, but relies, I think, on some procedures from Rx that
transform regular expressions to DFAs.  Any chance we can re-obtain
some lexing / parsing Guile modules at some point in the future?  (I
was setting about re-writing the DFA portions of Rx in pure Scheme --
the original just exposed some C functions).


On 5/24/05, Marius Vollmer <mvo@zagadka.de> wrote:
> Kevin Ryde <user42@zip.com.au> writes:
> 
> > Is the Rx regexp library supported in the guile core any more?  I
> > can't see it, and I think the docs for that stuff in the manual should
> > be removed to stop anyone getting confused between those functions and
> > the posix regex functions.
> 
> Ok.
> 
> --
> GPG: D5D4E405 - 2F9B BCCC 8527 692A 04E3  331E FAF8 226A D5D4 E405
> 
> 
> _______________________________________________
> Guile-devel mailing list
> Guile-devel@gnu.org
> http://lists.gnu.org/mailman/listinfo/guile-devel
>


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Re: doc rx regexps

[Neil Jerram]

Julian Graham wrote:
> Yeah, I noticed this too, while I was looking for a lexer tool for
> Guile and came across the old (lang lex) module.  (lang lex) is pretty
> straightforward, but relies, I think, on some procedures from Rx that
> transform regular expressions to DFAs.  Any chance we can re-obtain
> some lexing / parsing Guile modules at some point in the future?  (I
> was setting about re-writing the DFA portions of Rx in pure Scheme --
> the original just exposed some C functions).

FWIW, I'd like this too (but have no plans in the forseeable future to 
implement it).  How far off (or rotted) is the guile-rgx-ctax code in 
Guile CVS - does anyone know?

	Neil


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Re: doc rx regexps

[Tom Lord]

I'm not closely following this discussion but perhaps it 
would be helpful to point out that Rx is not currently 
distributed in an up-to-date form separately from other
projects.

Rx lives in something called `libhackerlab' which I maintain.
Up-to-date versions appear in projects such as GNU Arch.

I don't currently distribute `libhackerlab' separately.

So: if you have an Rx binding for Guile but aren't taking
the extra step of obtaining the latest Rx from my Arch archives
or from an Arch distribution, odds aren't bad that you'll wind
up with a known-bogus, older version of Rx.

I do happen to think that Rx is pretty great, if I am forgiven for
saying so myself.  It's a serious power tool: easy enough to 
hurt yourself with but also of very high utility.  My experiments
in Systas Scheme suggest that binding Rx to Scheme creates a 
functionally rich result and I strongly encourage people to explore
that combination.

I've lost track of where Guile is on shared substrings but I should
point out that Rx-in-Scheme is vastly more useful if at least
read-only shared substrings are provided.  (For example, the Posix API
to regexps returns integer offsets to indicate the positions of
matched subexpressions -- using shared substrings, strings can be
returned just as efficiently, sparing clients of the need to fuss with
integer offsets.)

But, one has to be cautious: be sure you are using an up-to-date Rx (and
that isn't *quite* trivial to do).

-t



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