[racket] Some design "whys" of regexps in Racket

From: Rodolfo Carvalho (rhcarvalho at gmail.com)
Date: Fri Jun 3 23:15:09 EDT 2011

On Sat, Jun 4, 2011 at 00:04, Eli Barzilay <eli at barzilay.org> wrote:

> Four minutes ago, Rodolfo Carvalho wrote:
> > On Fri, Jun 3, 2011 at 23:49, Carl Eastlund <cce at ccs.neu.edu> wrote:
> > > The origin of #px is "Perl-compatible regular expression", while
> > > #rx are compatible with command-line tools such as egrep.
> >
> > It seems that it's not yet documented. Good to know, now I can
> > choose between Perl and power :D
> See the top of http://docs.racket-lang.org/reference/regexp.html --
> it shows the basic shared syntax, and then there's
>  The following completes the grammar for regexp, which treats { and }
>  as literals, \ as a literal within ranges, and \ as a literal
>  producer outside of ranges.
> and a bit later
>  The following completes the grammar for pregexp, which uses { and }
>  bounded repetition and uses \ for meta-characters both inside and
>  outside of ranges.
> These blurbls summarize the difference, and the tables that follow
> them specifies the syntax formally.

Yes, I have that open here in another tab.
I read that before posting my questions.

What I pointed as "not yet documented" is the nomenclature "Perl-compatible
regular expression".
I just saw #rx, #px, their differences, and well, I even looked at *The
Reader*, but I didn't figure out what the p was for...

Thank you all for clarifying my doubts,


Rodolfo Carvalho
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