The Perl 6 summary for the week ending 2005-07-05
My, doesn't time fly? Another fortnight gone and another summary to
write. It's a hard life I tell you!
This week in perl6-compiler
Where's everyone gone?
It seems that most of the Perl 6 compiler development is being discussed
at Hackathons and IRC, and summarized in developers' weblogs. What's a
summarizer to do? For now, I'll point you at Planet Perl 6, which
aggregates a bunch of relevant blogs.
<http://xrl.us/gn5n>
PGE now supports grammars, built-in rules
Allison Randal raved about the "totally awesome" PGE grammar support. I
doubt she's alone in her enthusiasm.
<http://xrl.us/gn5o>
Multiple implementations are good, m'kay?
Patrick discussed the idea of a 'final' Perl 6 compiler, pointing out
that it isn't clear that there needs to be a "final" compiler. So long
as multiple implementations are compatible...
<http://xrl.us/gn5p>
Meanwhile, in perl6-internals
New calling conventions
Klaas-Jan Stol asked a bunch of questions about the new calling
conventions and Leo answered them.
<http://xrl.us/gn5q>
Parrot Segfaults
What's a tester to do? You find a bug that makes Parrot dump core, so
you write a test to document the bug and make sure it gets fixed. But
the test leaves core files lying about. It goes without saying that
Parrot should never dump core without the active assistance of an NCI
call or some other unsafe call blowing up in its face.
Which makes it a little embarrassing that PIR code generated by Pugs can
cause a parrot segfault, though that appears to have been caused by
mixed up calling convention style in the generated call.
<http://xrl.us/gn5r>
<http://xrl.us/gn5s> - Brian Wheeler's segfaulting Pugs script
Python PMCs
Leo pointed out that the various dynclasses/py*.pmc parrot support PMCs
don't yet support all the semantics that Python needs. He outlined some
outstanding issues announced that, as calling conventions and context
handling were changing he'd be turning off compiling py*.pmc for the
time being.
<http://xrl.us/gn5t>
PGE bug
It appears that the upcoming changes in Parrot's context handling tweak
a bug in PGE. The discussion moved onto a discussion of PGE's
implementation strategy, Nicholas Clark was keen to make sure it didn't
repeat some of the Perl 5's regex engine's infelicities. While this
discussion continued, Leo spent half a day with gdb and tracked down the
problem, which turned out to be that a register wasn't getting
initialized in the right place.
<http://xrl.us/gn5u>
Left-recursive grammars are bad m'kay?
While experimenting with PGE grammars, Will Coleda managed to write a
left-recursive grammar that blew Parrot's call stack with impressive
ease. Luke apologized for things blowing up so spectacularly, but
pointed out that left-recursive grammars weren't supported, and showed a
rewritten grammar that didn't have the same problem (but which doesn't
appear to match the same expressions).
<http://xrl.us/gn5v>
Coroutines
Leo pointed to a summary of coroutines, and noted that we still hadn't
defined the syntax of Parrot coroutines, especially with respect to
argument passing. He discussed it with Matt Fowles and solicited a set
of tests that expressed the semantics they came up with.
<http://xrl.us/gn5w>
<ftp://ftp.inf.puc-rio.br/pub/docs/techreports/04_15_moura.pdf>
ParTcl, Perl6 Grammars
Will Coleda announced that, thanks to Matt Diephouse's work, ParTcl (Tcl
on Parrot) is now able to run part of tcl's cvs-latest test suite. The
tests aren't fully native yet, they're currently driven through a Perl
test harness and only passing 10% of the tests, but hopefully the
situation will improve and ParTcl will end up able to run the tests
completely natively (while passing far more of them). Congratulations on
the work so far though.
<http://xrl.us/gn5x>
Python and Parrot
Kevin Tew popped up to say that he too is working on a Python compiler
targetting parrot and wondered how to handle things like Python's "self"
parameter. Michal Wallace and Leo chipped in with suggestions.
<http://xrl.us/gn5y>
Another month, another release
Has it really been a month? Seems so. Parrot walked through the
traditional feature freeze, code freeze before being released on Sunday.
The latest release is called 'Geeksunite', referencing the website that
discusses Chip's problems with his former employer. You should
definitely visit the Geeksunite site -- Chip needs our help.
<http://xrl.us/gn5z>
<http://geeksunite.org/> -- Support your local Pumpking
"lower" in default find_name scope
Patrick posted a code fragment whose output surprised him -- it turned
out that looking up "lower" as a name in the default scope returns an
NCI object. Leo explained why this was so, prompting Patrick to suggest
that it would be useful if, somewhere in the Parrot documentation there
was some descriptions of Parrot's builtin namespace. Leo encourage
others to comment on namespace issues, and hoped for some decisions as
well.
<http://xrl.us/gn52>
Copyrights
If you're like me, discussion of copyrights an licenses is the sort of
thing that either really winds you up, or induces serious drowsiness
depending on your mood as you read the thread. It's one of those "Too
important not to think about, but too tedious to think about any more
than is absolutely necessary" topics. That said, Will Coleda said that
he had thought that all of Parrot's code was supposed to have its
copyright assigned to the Perl Foundation. However, on inspection he
noticed a multiplicity of copyright notices in the actual code,
including one file in the repository with a Microsoft copyright.
<http://xrl.us/gn53>
PGE: Code blocks
Matt Diephouse wondered about the plan for integrating code blocks into
PGE. He thought it'd be nice to be able to specify a compiler to use
along with the code block (or, for the time being, just to be able to
use PIR code). Patrick said that there is a plan (or several) for
handling this, but getting blocks to work well needs coordination
between PGE and the compiler language. In essence, when PGE encounters a
code block it needs to hand off to the target language's compiler to
parse to the end of the code block, and get back from the compiler the
length of the block thus parsed.
<http://xrl.us/gn54>
Possible bug calculating denominators
Curtis Rawls posted a fragment of code that seems to break Inc's
"computed_denominators" algorithm. Leo wasn't surprised that there were
probably bugs in that part of IMCC, which was contributed by Angel Faus
who no longer seems to be participating in Parrot development. Which
means it's not been maintained for a while for lack of tuits. Anyone
with an appropriate supply of tuits is welcome (nay encouraged) to take
it on.
<http://xrl.us/gn55>
Meanwhile, in perl6-language
Type variables vs. type literals
Autrijus had a question about the difference between
sub (::T $x, ::T $y) {...}
and
sub (T $x, T $y) {...}
Larry answered about 4 times, mulling over various options. It's times
like this that I'm reminded why it's worth following the list in detail
rather than reading the summaries -- it's good to see Larry thinking
aloud, considering all sorts of (seemingly) wacky options and getting
feedback.
<http://xrl.us/gn56>
Mr Clean vs. Perl 6
Yuval Kogman had some comments about fascism, strong (but I think he
meant static) typing, cleaning products, Perl 6 and type inferencing.
Stephane Payrard hoped that "Perl6 could become the playground of type
theory searchers." (To which I can only respond with a highly personal
"Ick!")
<http://xrl.us/gn57>
Documentation trait / Docstring equivalent
The Platypus (aka David Formosa) wondered if documentation traits on
subs would be useful. The first to hope that it would be was chromatic,
commenting that it's a shame for Perl 6 to throw away potentially useful
data recklessly. Larry commented that he always cringes when he hears
"the documentation" as if it's the only thing. Again, Larry's thinking
aloud on this subject is well worth your time.
<http://xrl.us/gn58>
SMD is for weenies
So says Yuval Kogman, and who are we to doubt him? Yuval wanted to make
multimethods the default type. Sam Vilain disagreed, pointing up the
usefulness of warnings like "method foo redefined at ...".
<http://xrl.us/gn59>
DBI2 - The Plan and How You can Help
Tim Bunce outlined his current thinking on how DBI2 is going to work
(DBI2's going to be Perl 6 only) and a 'local' roadmap for the first
things that need doing. He then opened the floor for detailed proposals
for what a Perl 6 DBI API should look like. (I wonder if DBI2's going to
be an important enough tool that it'll want an RFC type process).
I'm glossing over the ensuing discussion -- it's at the stage where, if
you're interested, you're better off joining in directly.
<http://xrl.us/gn6a>
<http://xrl.us/gn6b>
Should ".assuming" always be non mutating?
Ingo Blechschmidt had some suggestions about the behaviour of the
currying method ".assuming", arguing that it should always return a new
thing and not alter the state of the underlying object. Larry agreed.
<http://xrl.us/gn6c>
"return()" in pointy blocks
Coo. the pointy block thread returns. The question is, where to?
<http://xrl.us/gn6d>
Time::local
Gaal Yahas announced that he'd added "localtime" to pugs in order to
address Dave Rolsky's needs when porting the very lovely and worth while
DateTime family of modules. He noted that Perl 6's final time related
interfaces were rather underspecified and had a bunch of questions. The
one thing that's absolutely certain is that the default Perl time API
will use subsecond resolution by default.
I've noticed that, every time you start to discuss how computers handle
'human' things like time, dates, or writing systems, people often seem
to have very strong and deeply held ideas of the Right Way of doing
things, and those Right Ways are almost all different. Larry's job is
probably going to be to work out the Least Wrong Way. (If you've not
heard Dave Rolsky's talks about the underlying reasons for writing
DateTime and the headaches it gave him then I suggest you seek it out).
<http://xrl.us/gn6e>
<http://xrl.us/gn6f> -- Perlcast 15, including Dave Rolsky talking about
DateTime
Autogenerated attribute accessor names
MetaModel maker, Stevan Little wondered what to do when attribute names
clashed as in:
class Foo { has @.bar; has $.bar; }
No answers yet.
<http://xrl.us/gn6g>
Acknowledgements, adverts, apologies and alliteration
Summarizing a week is definitely way easier than summarizing a
fortnight.
I'm apologizing in advance for the fact that, for those of you who read
this via the mailing list, some of the links probably don't work yet.
The thing is, the thread links are generated directly from the
message-id's because that's the information I have access to and, so far
as I know, Google Groups is the only archive that has a RESTful search
interface that lets me use message-ids as my key. If you know of an
archive site that does this, but is more timely in its archiving of
perl6-language in particular then please let me know and I'll start
using that instead. Ideally it should allow me to directly address as
message complete with its thread context.
If you haven't already done so you really should pay a visit to
<http://geeksunite.org/>. For the life of me, I can't see what I would
have done differently in Chip's situation and I'm staggered by what's
happened to him.
Right, back to our standard coda:
If you find these summaries useful or enjoyable, please consider
contributing to the Perl Foundation to help support the development of
Perl.
<http://donate.perl-foundation.org/> -- The Perl Foundation
<http://dev.perl.org/perl6/> -- Perl 6 Development site
Or, you can check out my website. Maybe now I'm back writing stuff I'll
start updating it.
<http://www.bofh.org.uk/>
Vaguely pretty photos by me can be found at:
<http://xrl.us/gn6h>
