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This week's summary

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From:
The Perl 6 Summarizer
Date:
July 6, 2005 08:07
Subject:
This week's summary
Message ID:
m264vokm6t.fsf@obelisk.bofh.org.uk
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>


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