Tag Archives: perl5

Perl6 hacking, grammars, Digest::MD5 and caffeine levels

I'll be brief. Need some sleep. :)

Perl 6 is here. Now. And there's an immense work waiting to be done: rewriting Perl5's CPAN. Ain't that easy? :)

Anyway, during last couple of weeks, I spent most of my spare time playing with Perl 6:


My poor excuse to (try to) learn grammars was to build a Perl6 class that could parse a puppet module and build some documentation for it. Puppet itself uses a grammar to parse its modules, so I thought it wouldn't be impossible to port it to Perl6 and use it to parse puppet code.

Well, turns out it's not so easy, but at least I'm learning how grammars work and having fun.

Perl6 Digest::MD5

This is extremely fascinating, because it's touching the Parrot core. In Parrot, there's already a Digest::MD5 module, so all you have to do (but again, not so easy), is to write a Perl6 "wrapper" around the Parrot code.

And how do you do that? With PIR blocks. This stuff is great. Seriously. It's like going back to Assembly, in some sense(tm). Here's an example of this glue PIR code:

class Digest::MD5 {

    multi method md5_hex (Str $message) {


        my $md5_sum = Q:PIR {
            .local pmc md5sum, md5_sum_get
            md5sum = get_root_global ['parrot'; 'Digest'], '_md5sum'
            $P0 = find_lex '$message'
            $P1 = md5sum($P0)
            md5_sum_get = get_root_global ['parrot'; 'Digest'], '_md5_hex'
            %r = md5_sum_get($P1)

        return $md5_sum;

    multi method md5_hex (@message) {
        my Str $message = @message.join('');
        return Digest::MD5.md5_hex($message);


Even if you don't understand Perl 6 or PIR, you can probably recognize a class definition, and polimorphic methods. md5_hex() is in fact defined twice:

  • multi method md5_hex (Str $message)
  • multi method md5_hex (@message)

You don't have to write polimorphic methods, but you can do it if you want. Yes, there's more than one way, and there always will be. I don't like dictators, even if they are benevolent, and Python code looks so flat and dull, seriously. There's no personality in Python code. Yes, sigils are great.

Digest::MD5 is also using alien technology (UFO).

Synopsis documents

Nothing fancy there, just improved the existing CSS. For an example, go read Synopsis 03 about operators.

Good night!