In late November 2007 Jonathan Worthington submitted a Hague Perl 6 Grant proposal entitled 'Rakudo Dispatch and Role Enhancements'. I am pleased to announce that Jonathan submitted his final Hague grant report yesterday (included below the fold), and it was approved and accepted by chromatic, the grant manager for the grant. This successfully completes this Hague Grant for Perl 6 development. We thank Jonathan for his great work on this grant and his efforts in advancing the goal of a completed Perl 6 implementation.
In the months during which I have worked on my Hague Grant, Rakudo Perl
6 has taken some huge steps forward - not just as a result of my work
and this grant, but as the result of the efforts of a growing Rakudo
Perl 6 user and developer community. When I submitted my grant proposal
I noted that we passed over 4,000 tests. Today we pass over 10,000, are
more stable and have a much wider feature set. Thus my work on the
deliverables of this grant have been part of a wider scene of extensive
All deliverables have been achieved. In places, my work has gone beyond
what the grant required. Reactions to my work have been positive, both
from users and other developers.
D1. We now register types in the symbol table at compile time and the
hack that saw us through the early days is removed. Furthermore, I have
used this to build some other features, including compile time detection
of type re-declaration.
D2. Junction auto-threading is now fully implemented for both single and
multiple dispatch. The Perl 6 multi-dispatcher knows how to generate and
cache junction dispatchers for future performance too. As various
built-ins have moved over to the Perl 6 prelude, they too have gained
the auto-threading automatically. I also reviewed and added a range of
tests1 to exercise the auto-threading, including ensuring that
interaction with multis and auto-threading as well as nested junctions
work as expected.
D3. I implemented submethods and reviewed and enabled the tests for them.
D4. The handles trait verb has been extensively refactored and now
handles many more cases. I reviewed, enabled and added to the spectest
suite tests2 relating to this, to improve test coverage.
D5. This has by far been the most significant and complicated
deliverable of the grant, and what has been achieved in this area
exceeds what was originally required. First and foremost, we now have an
implementation of parametric roles. They can be declared, composed and
mixed in, the selection falling naturally out of the usual
multi-dispatch semantics as is specified.
In addition to this, I have converted the Positional, Associative and
Callable roles to be parametric. This, along with a little bit of extra
work in the compiler, has now given us typed arrays, hashes and routines
- features from S09 and S06. This has served as a great concrete test of
parametric roles. It has also won us sigil-based multi-dispatch and
multi-dispatch based upon typed data structures too.
Test coverage for parametric roles was weak (understandable, because
nobody had implemented them before), and I have expanded this greatly
during my work3,4,5. Some tricky areas - including parametric roles
recursively parametrized and parametric role subtyping - a feature not
in the specification at the time I started the grant - are now well
I rounded this work off by updating S146 (the specification for roles,
which has been broken out from S12 since I started this grant). It is
now more detailed and complete.
I have written several blog posts on use.perl.org7 and rakudo.org
during my time working on this grant.
I have remained active on the #perl6 channel, explaining my work to
people there as they asked questions. I have also spoken on Perl 6 at
four workshops8 during the duration of the grant, and covered the work
I have been doing there. I also attended the Nordic Perl Workshop
hackathon to get feedback from Larry and tie up some of the last loose
ends in parametric roles.
My work under this grant has moved Rakudo forwards, not just in the
things listed in the deliverables but also in many tangential things
that I did along the way to enable me to make progress on the grant too.
Overall - despite finishing a little later than originally planned - I
feel that this grant has been a success and a win for Rakudo.