It’s finally time for the State of the Onion. Larry Wall introduced this year’s theme, Rules That Are Meant to be Broken.

If he had Perl to do all over again, what would he do different? Only two things, nothing, and everything. Perl 6 is the everything part of the answer.

In Perl 5, one of the problems that creeps up is that regular expressions (regexes) are strings. The best example of this is variable interpolation in regexes. In Perl 6, this has been fixed. They are now their own language.

Like cargo-cult programming, parsing has turned into its own cargo-cult. Perl 6 breaks the mold when it comes to copying languages (the old lex/yacc loop), and instead uses polymorphism in its sub-language design.

Both regexes, double quoted strings, and single quoted strings are examples of sub-languages in Perl 6. Each of these sub-languages has its own parsing rules and therefore parsing implementations. This allows is code reuse. Parsers can derive behavior from other parsers, but treat the tokens differently as necessary.

Fundamentally, Perl 6 is very simple. It has no CORE. It has no built-ins and no operators. What Perl 6 has given us (will give us?), in effect, is a just in time lexer. Tokens and their behavior can be defined on the fly, on a per-sub-language basis.

There are quite a few changes to the regularity of regular expressions. Mostly what this means is that Perl 6 regexes are incompatible with those used in Perl 5, and that Perl-compatible regular expressions (PCRE) aren’t (or won’t be).

All languages tend to fall into the One True Syntax trap. Perl 6 has aimed to break out of that trap. By giving the user enough power over the syntax (rope) to design the language that suits them (hang themselves).

I didn’t enjoy the State of the Onion as much as I have in the past. I suppose that’s to be expected. Larry did warn us at the top of the talk that it would be serious and contain only a single joke. For as great a writer as Larry is, his ability as a public speaker is lacking. That’s okay, though. I’d rather he not shift focus away from the design and development of Perl.

[tags]oscon, oscon08, oscon2008, Perl, State of the Onion, Larry Wall[/tags]