(cross-posted from http://pugs.blogs.com/pugs/2006/03/a_tale_of_two_p.html-- this provides some background of the ongoing Vienna^2 hackathon's progress on bootstrapping Pugs on Perl 5 and Parrot, simultaneously, sharing as much code and structure as possible.)
Just some short sketches as I'm quite exhausted after another day of nonstop hacking. Ingy and I generalized the "use v6-pugs" concept into Filter::PMC<http://svn.kwiki.org/ingy/Filter-PMC/lib/Filter/PMC.pm>, taking advantage of Perl 5.6+'s feature that when you say "use Foo", it looks *first* at the Foo.pmc file, and only if it's stale or nonexistent (which is, like, always), will it load Foo.pm. See fglock's ongoing work on Pugs::Grammar::Rule<http://svn.openfoundry.org/pugs/perl5/Pugs-Compiler-Rule/lib/Pugs/Grammar/>for the zeroth application of this idea -- Rule.pm<http://svn.openfoundry.org/pugs/perl5/Pugs-Compiler-Rule/lib/Pugs/Grammar/Rule.pm>is processed on author's side, and Rule.pmc<http://svn.openfoundry.org/pugs/perl5/Pugs-Compiler-Rule/lib/Pugs/Grammar/Rule.pmc>is uploaded/installed along with it, so the user won't need a copy of pugs, or an installed version of v6.pm -- it's all just pure Perl 5 code. This is wonderful news, as it solves four major problems for source-filterish technlogies like Inline<http://search.cpan.org/dist/Inline/>, Spiffy <http://search.cpan.org/dist/Spiffy/>, Switch<http://search.cpan.org/dist/Switch/>(and of course, *v6*): - The user doesn't need to install the filtering modules themselves; the .pmc code is precompiled into normal Perl 5 code. - Debugging is now much easier, as you have both the original and transformed programs available. - Embedded Perls (say in mod_perl) can load them without triggering INIT problems, as the .pmc are just regular Perl code. - Finally and most importantly, this makes source filters *composable*, and you can have nested chunks of layered compilers inherits or delegates to each other. This is great for eg. porting the Perl 6 macro system to Perl 5. As a consequence, the release of v6.pm and Pugs::Compiler::Rule has been delayed for one day, so that we can have more robust cross-validation between .pm and .pmc files, and have them play nicely with other Filter::PMC technologies. In other news, Leo and I populated the *languages/pugs/* tree in Parrot, bringing in all the Value PMCs<http://svn.perl.org/parrot/trunk/languages/pugs/pmc/>we need for bootstrapping PIL^N on Parrot. We just need to figure out Pad/Namespace storage and primitive mappings, and we'll instantly get a running Perl 6 object space -- with Classes and Roles -- on top of parrot. The porting of Value PMCs largely involves finding a base PMC type and extend from it, although Parrot's notion of treating all PMCs as scalar/array/hash/sub/ref *containers* means we'll get some oddities in the object model: - *"1.id == 1.id"* doesn't hold, as two boxing attempts always produce two PugsInt objects - "*int('12345678901234567890')*" overflows, as PugsStr cannot coerce to PugsInt, and always have to go through a native I register (which is limited in size) - "*given 1 { $_++ }"* won't throw an exception, and will indeed * silently* change the "1" in-place! It'd make more sense if a PMC can declare that it's not a container at all, and avoid the FETCH/STORE type vtable entries altogether, or at least declare it only supports one container interface or the other. I've submitted an overview on perl6-internals<http://www.nntp.perl.org/group/perl.perl6.internals/33240>as well. That's it for today. See you tomorrow!
