Pugs

The Perl 6 summary for the month of May 2006

Summary updates

This post continues with the task of addressing the Perl 6 summary backlog.  The following schedule is planned for the remaining updates:

• 6 August: June
• 13 August: July
• 20 August: August to date

After the 20th of August I hope to return the summaries to a weekly schedule.

Moose... it's the new camel.

Aside from a cameo appearance in my RHOX talk, Moose.pm saw a couple more interesting mentions in this year's OSCON.

The first is TimToday++'s State of the Onion talk.  He explained the now-slightly-less-imaginary Perl 6 Timeline, as well as the v6.pm stack, then went on to say that Moose.pm is his favorite piece in the 6-on-5 puzzle.

The next day, Tim Bunce discussed the plan toward DBI 2.0 as a lightning talk.  It's very exciting to hear that the new version of DBI will clearly be based on Moose, in particular using its Role support to offer a better interface.  Yay for the lambdamoose! :-)

RHOX slides available!

I've just finished delivering the talk; it went very well, though quite exhausting -- I feel as if I've just delivered 9 lightning talks in a row.

Slides are available in the usual formats: PDF, Flash, HTML+Images.  If you haven't read Jesse's Jifty talk, please read that first (it's .xul -- needs a Mozilla-based browser).

By going with the lighting talks style, at each section the audience seems to be evenly split between actively excited and totally lost. I wonder if I'll do better if I cover just half the material...

Oh, and I just discovered I have another lightning talk (ppencode) to give.  Well, at least this one is just five minutes, and I already go the slides ready. :-)

Perl 6 is coming (to the SysAdmin magazine).

Yay, merlyn++'s wonderful article is now available online!  I attended his and bdfoy++'s "Learning Perl 6"
course at YAPC::NA, and I'm really amazed of their ability to explain concepts so effectively.

Also, the instructor point-of-view is helpful to language design as well: For example, merlyn++ noted that the ==> and <== operators, known as the pipe operators, is likely to cause confusion with Unix pipes. Because they are shipping concrete objects instead of stream-of-characters, now they are renamed feed operators.

Another example: The implicitly-passed-with-each-calls variables were known as environmental variables, and declared with "env $x".  However, merlyn++ noted that it can easily be confused with environment variables in %*ENV.  So they are now contextual variables, and declared with "my $x is context".

...and now I stop procrastinating and go back to my slides...

The night before the "Jifty RHOX" talk.

I took the evening off from making slides, and went to see three great talks from Larry, Kathy and Damian. I very much did not regret going there, but that does mean I'm woefully behind on slides again:

Be as it may, here is what little I have so far -- I'll try to sleep a bit and finish them in the morning.  Wish me luck! :-)

v6.pm: 920 tests pass!

Some power of Mystery dragged Chia-Liang Kao, maker for our version control system svk, into hacking v6.pm over the weekend with fglock.  See his use.perl journal post for a quick walkthrough into v6.pm hacking!

The Perl 6 Summary for April 2006

Perl 6 Summary - March 2006.

Hs -> P6

When I was giving a talk at YAPC, someone asked me if a Haskell data type is like a blessed object in Perl. I said that they were profoundly different. Well, that was probably too offputting: a Haskell datatype can be represented as a Perl 6 Role, and its variants as different Classes.

To facilitate the Perl 6-on-Perl 6 efforts, Audrey asked me to write a general automatic DrIFT-based Hs->P6 converter. The first use is to put the new AST scheme in a language where data can be more readily manipulated. For example, here is a function parameter in both Haskell and Perl 6:

-- Haskell
data Param = MkParam
    { p_variable    :: Ident
    , p_types       :: [Class]
    , p_constraints :: [Code]
    , p_unpacking   :: Maybe Sig
    , p_default     :: Maybe Exp
    , p_label       :: Ident
    , p_slots       :: Table
    , p_hasAccess   :: ParamAccess
    , p_isRef       :: Bool
    , p_isLazy      :: Bool
    }

# Perl 6
role Param is TaggedUnion;

class MkParam does Param {
    has Ident $.p_variable;
    has Class @.p_types;
    has Code @.p_constraints;
    has Sig $.p_unpacking;
    has Exp $.p_default;
    has Ident $.p_label;
    has Table $.p_slots;
    has ParamAccess $.p_hasAccess;
    has Bool $.p_isRef;
    has Bool $.p_isLazy;
};

Here is the latest AST translation (and where that came from). This is a step towards assuring that Pugs' Perl 6 AST can be shared by other implementations, and (for example) macros that manipulate parsed bits of Perl can work on more than one compiler.

So far this was much easier to do than our YAML class (that bridges why++'s libsyck with Haskell for any data). But the next step is figuring out how to dump actual arbitrary Perl 6 values...

Pre-OSCON intermission.

Still working on my slides (modulo the occasional perlmonks post), so updates in this space will be slower than usual.

Sadly, our IRC logger is currently down.  Here is a short recap from #perl6 logs:

• Sage++ is using Parsec to parse the Perl 5 regex syntax and  got most of them translated to Perl 6 regex in his  P5toP6 translator,
• scw++  meanwhile worked on translating Perl 6 regex and embedded MiniPerl6 into Haskell's Parsec syntax.  (Mmm circularity.)
• gaal++ worked on getting the new AST to compile (as Haskell and emit as Perl6/Moose classes), cutting down hundreds of type errors  to a couple of them.
• TimToady++ hacked the spec to introduce repeat while loops, resolving an issue raised by a recent p6l thread.  Then he hacked the test suite to reflect the new syntax so they fail. Then he hacked Pugs.Parser so it now supports the spec... and the tests pass again.  Yay!

Now I'll go back to make slides for the "Jifty RHOX my $Job" talk.  (i.e., "How Jifty tamed the Relational/Hypertext/Object/XML mismatch for my day job.")  See you at OSCON!

XML::Literal 0.01.

As part of today's work on my OSCON slides,  I've put XML::Literal 0.01 on CPAN:

# This is not a source filter: it just augments glob().
use XML::Simple;
use XML::Literal \&XMLin;

# Simple element
my $xml1 = <hr/>;

# With variable interpolation
my $xml2 = <input value='$ARGV[0]' />;

# With an extra pair of angle brackets
my $xml3 = < <a href='/'> Some Text </a> >;

# With escaped angle brackets 
my $xml4 = <a href='/'\> Some Text \</a>;

# Direct call to the xml-building glob'' constructor
my $xml5 = glob'
    <p><em>
        Some Text
    </em></p>
';

# This does not look like XML, so it's still shell glob
my @files = <*.*>;

Of course, having it simply construct hashes via XML::Simple is not  very interesting. More fun is to use it to construct XML patterns and composable, self-validating fragments -- more (ab)uses are left as exercise for the reader. :-)