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

On Fri, Jun 3, 2011 at 10:46 PM, Rodolfo Carvalho <rhcarvalho at gmail.com> wrote:
>> > 2) Why there are two kinds of regexps, #rx and #px?
>> > #rx"\\d{2}" doesn't work because the curly braces are part of just
>> > pregexps
>> > grammar...
>>
>> #px is more powerful than #rx, but that power costs. Most regexps can
>> get by with what #rx has.

The origin of #px is "Perl-compatible regular expression", while #rx
are compatible with command-line tools such as egrep.

--Carl