Perl 6 mailing list summary, 24-30 September, 2006

  This week on the Perl 6 mailing lists

     "And here I thought you were a responsible, law-abiding citizen... :P "

     -- Jonathan Lang, commenting on Larry Wall's `self.HOW does Hash`


  Language

   class interface of roles <http://xrl.us/rzbh>

     TSa wondered how typing of mixins <http://xrl.us/rzbi> would look in
     Perl 6. A code example of how it might look was included. There were
     also some questions on roles in Perl 6.

   Capture Literals <http://xrl.us/rzbj>

     Responding to an earlier thread, Austin Hastings asked if Capture
     literals would replace or unify "assuming"/"currying".

   Motivation for /<alpha>+/ set Array not Match? <http://xrl.us/rzbk>

     In a previous week, Audrey Tang quoted a section of S05 concerning
     subrules. She found the 'quantified' clause to be unintuitive and
     wondered if it would be possible to modify it to produce Match objects
     and to reserve Array only for noncontiguous same-name subrules.
     Patrick R. Michaud and Flavio S. Glock made some alternate
     suggestions.

     More recently Audrey replied to the thread, wondering if there was a
     hidden cost to making `/<foo>+/` always react so that `$<foo>.from`
     returns something. Masak preferred the proposed semantics and asked if
     the question had been discussed off-list.

   Nitpick my Perl6 - parametric roles <http://xrl.us/rzbm>

     Sam Vilain sent some code on Perl 6 core types as collections and
     asked if anyone would like to poke holes in it. TSa applauded the use
     of functions but wondered if it would work. Several other people
     followed up on that thought.

   Mutability vs Laziness <http://xrl.us/rzbn>

     Aaron Sherman pursued a conversation which began in IRC. He listed
     some immutable types declared in S06 and noted that there appear to be
     three core attributes (Mutability, Laziness and Ordered), each of
     which has two states (true or false). From this he derived 8 types of
     containers.

     Dave Whipp thought there was a fourth attribute, exclusivity. Sam
     Vilain felt that ordered was not an attribute of a collection.

   [svn:perl6-synopsis] r12398 - doc/trunk/design/syn <http://xrl.us/rzbo>

     In a recent commit, Larry Wall removed the special `[,]`, which is now
     just a list op form of `[...]`. In order to support the `|func()`
     syntax, `|` became the new disigilized `*`.

     Luke Palmer replied in support of the new syntax. TSa also approved,
     but would have liked the new operator spelled. Aaron Crane thought
     that was undesirable because there are already terms which begin with
     `/`, namely regular expressions.

   Common Serialization Interface <http://xrl.us/rzbp>

     Brad Bowman wondered if there was a common element to a serialization
     role which could be included in the default implementation. Mark
     Stosberg noted that there is already a `.yaml` and a `.perl` to
     serialize to these formats, but he did not know if they were suitable
     substitutes for the role-based approach Brad had in mind. He included
     a code sample. Aaron Sherman and Luke Palmer offered additional code
     examples. Larry Wall commented that it makes a big difference whether
     the entire string must be held in memory or not.

   [svn:perl6-synopsis] r12417 - doc/trunk/design/syn <http://xrl.us/rzbq>

     Audrey Tang committed a change which introduced the `$$x` form in
     adverbial pair parsing to S02 and canonicalized the term 'item' in S02
     and S04.

   [svn:perl6-synopsis] r12432 - doc/trunk/design/syn <http://xrl.us/rzbr>

     In S03, Audrey Tang noted that chained comparisons short-circuit and
     never evaluate arguments more than once.

   RFC: multi assertions/prototypes: a step toward programming by contract
   <http://xrl.us/rzbs>

     Aaron Sherman wrote to suggest a signature prototype that all multis
     defined in or exported to the current namespace must match, as a means
     of implementing the paradigm of programming by contract.

     Trey Harris felt that the point of multiple dispatch is that arguments
     are not bound to a single type, and the proposal might defeat this
     use, although junctive types, subsets and roles make 'single type'
     less of a constraint. Miroslav Silovic was bothered by the possible
     duplication of functionality and believed that declarative
     requirements should go in to roles. Many other people responded to
     this thread.

     In addition, there was a discussion on the terminology of libraries in
     Perl 5 and Perl 6--'package' being the Perl 5 term, and 'module' the
     Perl 6 term. The definition of 'programming by contract' was also
     discussed.

     There was also a discussion on whether 'package' implied a Perl 5
     library and 'module' suggested a Perl 6 one. Larry Wall attempted to
     clarify.

   special named assertions <http://xrl.us/rzbt>

     David Brunton posted about an IRC conversation from earlier. He listed
     the seven special named assertions found in S05, and the twenty-four
     found in `docs/Perl6/Overview/Rule.pod`. He found another one in
     `t/regex/from_perl6_rules/stdrules.t`. In his opinion, it was worth
     creating a single place in S05 where all of these named assertions are
     listed.

     Patrick R. Michaud disagreed with the inclusion of `<'...'>` and
     `<"...">` as named assertions. He stated that he would compare the
     list with what PGE has implemented and report differences. Mark A.
     Biggar noted that the documentation should distinguish between
     pre-defined character classes and special builtins. Patrick responded
     with PGE's view on what constitutes a special builtin.

  Parrot Porters

   A dedicated per-context stack for bsr/jsr/ret <http://xrl.us/rzbx>

     Bob Rogers sent a patch to create a `return_stack` for `bsr/jsr/ret`
     ops. Leopold Toetsch replied that separate stacks are good, but
     wondered if a return stack per context was desired. Bob Rogers replied
     in detail and included another patch.

   postgres interface <http://xrl.us/rzby>

     Leopold Toetsch has been working on `postgres.pir` and reported
     several changes, including a new test file. Bob Rogers sent a patch to
     make it more forgiving of an absent `libpq.so`. It was applied.

   [perl #40410] Segfault in packfile code <http://xrl.us/rzbz>

     In ticket [perl #40410] <http://xrl.us/rzb2>, Jonathan Worthington
     reported a segmentation fault in generating a packfile for compiled
     PIR generated by .Net. Later he found the bug and implemented a
     workaround.

   FYI improved pugs smokes <http://xrl.us/rzb3>

     Leopold Toetsch referred to the recently improved smoke tests for
     Pugs, and wondered if it would be possible to do something similar for
     Parrot. Jerry Gay replied that he'd been working on a Parrot
     implemention.

   External PDD Checkin <http://xrl.us/rzb4>

     chromatic reported that he had added details to the external API draft
     PDD and welcomed comments on `docs/pdds/clip/pdd10_embedding.pod`.

   [PATCH] Parrot-Embed on Win32 <http://xrl.us/rzb5>

     François Perrad supplied a patch to make Parrot-Embed compile and run
     on Win32.

   FYI compiling PIR function calls <http://xrl.us/rzb6>

     Leopold Toetsch wanted people to know about alternate syntax for
     generating PIR calls from a compiler:

     `.pcc_begin

     .arg "hello"

     .arg "n"

     .invocant obj

     .meth_call "_meth"

     .result $S0

     .pcc_end`

     Allison Randal replied that she felt the problem was one of
     inconsistency. She gave a few suggestions, which Leopold Toetsch
     responded to. Jonathan Scott Duff also proposed a slight modification
     of syntax. A discussion on the syntax followed.

   [svn:parrot-pdd] r14741 - in trunk: . docs/pdds/clip
   <http://xrl.us/rzb7>

     Allison Randal made some modifications to PDD22 to create a first
     release candidate of the I/O PDD.

   A moment of Zen <http://xrl.us/rzb8>

     Allison Randal posted that the single most important thing in the
     project is shipping a 1.0 release of Parrot, which is now very close.
     She called for functionality over elegant theory for the moment.

   call/return and CPS <http://xrl.us/rzb9>

     Watson Ladd asked how call and ret opcodes will interact with
     continuations. chromatic replied that the opcodes invoke the
     appropriate continuations.

   PDD 22 - I/O release candidate 1 <http://xrl.us/rzca>

     Allison Randal announced that she'd committed an updated I/O PDD. She
     requested feedback, especially on which lightweight concurrency model
     to use for asynchronous operations. She also asked for a reaction on
     async ops returning status objects while sync ops return integer error
     codes.

     chromatic suggested that ops could always return PMCs, and simply
     check the intval if required. Tim Bunce wondered if speed-sensitive
     ops which might be used in loops could be given the PMC to reuse.

     Leopold Toetsch remarked that he did not like I/O opcodes and
     explained why. chromatic disagreed with one of the arguments and
     Leopold replied.

     Joshua Hoblitt asked for more details on Allison's comment about
     concurrency models: was she speaking of the Parrot API, the actual
     implementation, or both? He felt that the implementation would need to
     be highly platform specific.

   [CAGE] perl coding standards... <http://xrl.us/rzcb>

     Will Coleda created a perlcritic tests, `t/codingstd/perlcritic.t`,
     which isn't run by default. It currently reports only a few rules. He
     suggested that Cage Cleaners could run this test to receive a long
     list of things to fix. He offered some advice on addressing the issues
     which show up.

   [perl #40419] 2 PDD 07s <http://xrl.us/rzcc>

     In ticket [perl #40419] <http://xrl.us/rzcd>, Will Coleda reported
     that there are two PDDs numbered 07.

   Prototyping variable-sized PMCs <http://xrl.us/rzce>

     Allison Randal summarized a telephone conversation with Leopold
     Toetsch. They discussed proposals on variable-sized PMCs and a shared
     base class for PMC types ('Two new pdds <http://xrl.us/rzcf>'). In
     Allison's opinion, variable-sized PMCs are a step toward closing the
     gap between low-level PMCs and higher-level Parrot Object PMCs. She
     also thought there were several good ideas in the shared base class
     proposal. The new PMCs will be implemented first as prototypes, and
     assessed/rewritten without changing the existing system.

   Two new pdds <http://xrl.us/rzcf>

     Leopold Toetsch announced two new documents in `docs/pddfs/clip` as of
     r14774. One, `pddXX_cstruct.pod` is the metaclass of all publically
     accessible C-derived structures used in Parrot. The other,
     `pddXX_pmc.pod`, describes the general structure of PMC internal
     layout.

     Jonathan Worthington replied to the commit ([svn:parrot-pdd] r14774 -
     in trunk: . docs/pdds/clip <http://xrl.us/rzqk>) to give his thoughts
     on Leopold's proposals.

     A related thread is 'Prototyping variable-sized PMCs
     <http://xrl.us/rzce>'.

   FYI: $job <http://xrl.us/rzcg>

     Leopold Toetsch announced that his job will require him to reduce his
     Parrot commitments, but that he would continue to follow development
     as time permits. Allison Randal thanked him for his contributions.

   socket related constants <http://xrl.us/rzch>

     Nicholas Clark replied to an older thread. He said that there are two
     problems to be solved, namely parsing C header files and identifying
     the constants, and injecting identified constants in to Parrot
     appropriately. Nicholas explained a little about how this is going in
     Perl 5.10.

     Joshua Hoblitt was reminded of the question of whether anyone had
     looked at APR for doing portable I/O.

   [HOWTO] call a method on a PMC in PIR <http://xrl.us/rzck>

     Karl Forner wanted to call the `elements()` method on a
     FixedBooleanArray, or add a custom method `get_allocated_size()` to
     the FixedBooleanArray.pmc. Leopold Toetsch replied with suggestions.

   Draft of Bytecode PDD <http://xrl.us/rzcm>

     Allison Randal announced that Jonathan Worthington had written a draft
     PDD for Parrot's bytecode format, which was checked in as
     '[svn:parrot-pdd] r14784 - trunk/docs/pdds/clip <http://xrl.us/rzco>'.
     Later some additional changes (based upon a conversation with Allison)
     were also committed.

     In 'Bytecode PDD <http://xrl.us/rzcq>' Jonathan asked for feedback.
     Leopold Toetsch offered a few comments.

     Ben Morrow wanted to know if pbc files could allow an optional `#!`
     line so that they could be used as executables. Jonathan replied that
     he had considered this, but rejected it because it is UNIX-specific.
     There was additional discussion on the topic.

   requirements gathering on mini transformation language
   <http://xrl.us/rzcn>

     Allison Randal asked for a volunteer to write up the requirements for
     a mini transformation language to use the compiler tools. The job
     would involve spending time with Allison and Patrick Michaud and
     combining their ideas along with your own perspective. Adriano
     Ferreira offered some opinions on the subject, and Markus Triska
     volunteered to do it if it relates to his area of expertise.

   [perl #40428] [PATCH] Return perl script and module file locations in
   parrot distro <http://xrl.us/rzcr>

     In ticket [perl #40428] <http://xrl.us/rzqm>, Paul Cochrane submitted
     a patch to return the names and locations of the perl script and
     module files within the Parrot distribution.

   [perl #40429] [PATCH] test for perl code coda <http://xrl.us/rzcs>

     Paul Cochrane supplied a patch in [perl #40429] <http://xrl.us/rzqn>
     to add a test for the Perl code coda. Will Coleda rejected the patch
     because he'd just added the same test as a Perl::Critic policy class.

   [perl #40430] [PATCH] rename and update C code coda test
   <http://xrl.us/rzct>

     Paul Cochrane renamed the C coda test and removed Perl-specific code
     from the test. It was applied as r14812. The ticket for this patch is
     [perl #40430] <http://xrl.us/rzqo>.

  Users

   How to pass a ref from a language with no refs <http://xrl.us/rzcu>

     This week the long-running CGI thread splintered in to the question of
     how to pass a reference from a language with no references when Mark
     Stosberg replied to a discussion on how Perl 5 embeds in Perl 6.

     Mark saw some recent Pugs commits on Perl 5 embedding, which
     encouraged him to experiment with passing hashes and arrays. In his
     tests, he was able to send an array as an arrayref, but was unable to
     get a hashref. He wondered if there was another way to do it.
     Aristotle Pagaltzis replied.

   Perl6 "style-guide" <http://xrl.us/rzcv>

     Last week, Fagyal Csongor asked if someone was willing to write a Perl
     6 style guide. This led to a discussion on other resources, desired
     and existing. This week, Chris Dolan asked if anyone wanted to start a
     port of Perl::Critic.

   xx operator <http://xrl.us/rzcx>

     Fagyal Csongor included some code which gave an unexpected result and
     wondered if the code or Pugs was at fault. A. Pagaltzis replied that
     the `xx` operator is list-repeat rather than string-repeat. Juerd also
     explained further, and the code was fixed.

  Acknowlegements

     This summary was prepared using Mail::Summary::Tools
     <http://xrl.us/rzcz>, now available on CPAN.

     If you appreciate Perl, consider contributing to the Perl Foundation
     <http://donate.perlfoundation.org> to help support the development of
     Perl.

     Jamie Cheetham supplied server access this week.

     Thank you to everyone who has pointed out mistakes and offered
     suggestions for improving this series. Comments on this summary can be
     sent to Ann Barcomb, <[email protected]>.

  Distribution

     This summary can be found in the following places:

     * use.perl.org <http://use.perl.org/>
     * The Pugs blog <http://pugs.blogs.com/>
     * The perl6-announce mailing list <http://xrl.us/rzc2>
     * ONLamp <http://www.oreillynet.com/onlamp/blog/>

  See Also

     * Perl Foundation activities <http://blog.perlfoundation.org>
     * Perl 6 Development <http://dev.perl.org/perl6>
     * Planet Perl Six <http://planetsix.perl.org/perl6>