Regular Expression Mastery

Perl 6

Perl has a (deserved) reputation for having too much punctuation
- A lot of that reputation is based on Perl's regex syntax
- But a lot of the regex syntax was inherited from Ken Thompson's original design
- He used up all the brackets for things like quantification
- All that was left were things like (?:...)
Perl 6 will completely overhaul its regex syntax
- Patterns will become much more like BNF grammars
- They will efficiently incorporate other patterns as sub-parts:

        rule octet { \d <1,3> }
        rule ip_address { <octet> [ \. <octet> ]<3> }

        $ip_address = /\d<1,3>[\.\d<1,3>]<3>/;

        $ip_address = m:p5/\d{1,3}(?:\.\d{1,3}){3}/;

See http://www.perl.com/lpt/a/2002/06/04/apo5.html for the fascinating details