The Perl 6 Summary for the week ending 20021208
Another Monday evening. Another summary to write.
Starting, as is becoming tediously predictable, with perl6-internals.
Another JIT discussion
Toward the end of the previous week, Leopold Tötsch posted something
about the latest round of changes to the JIT core. Daniel Grunblatt was
concerned that the current JIT wasn't doing the right thing when it came
hardware register allocation and wanted to remove a some conditional
logic. Leo didn't agree at first, but became convinced and Daniel's
requested change was applied.
http://makeashorterlink.com/?P4AB24AB2
Fun with IMCC
Lots of things happened with IMCC this week:
* David Robins posted a list of minor niggles (For instance, it turns
out you can't "ret" early from a ".sub") and suggested some
remedies. Leo Tötsch mentioned that the IMCC Cabal (which would
consist of Melvin Smith, Sean O'Rourke, Angel Faus and Leo if there
were a Cabal. But, as everyone knows, There Is No Cabal) have been
discussing several of these issues.
http://makeashorterlink.com/?Q1BB22AB2
http://makeashorterlink.com/?W1CB43AB2
* Art Haas had problems building IMCC, apparently bison didn't like
the imcc.y file. Leo tracked down the problem (at the second time of
asking, I think he might be slipping) and checked in a working fix.
* Leo Tötsch made a pile of changes to IMCC to eliminate clashes
between Parrot's PASM language and IMCC's PIR syntax, which had made
it hard to mix the two. Full details of the changes are in his post.
Gopal V wondered if there was any way of feeding code to IMCC beyond
simply writing to a file and running IMCC. He'd had to make a bunch
of changes to the IMCC files that he used, and wondered if there was
a Better Way. Actually he didn't so much wonder as propose the
aforementioned Better Way, lifting ideas from DotGNU's treecc. He
and Leo discussed things, worked out an interface and Gopal went off
to implement something (Yay Gopal!)
http://makeashorterlink.com/?Y1DB21AB2
http://makeashorterlink.com/?A6EB42AB2
* Steve Fink posted a patch implementing a first cut at namespace
support in IMCC. He wasn't at all sure that what he'd implemented
was the Right Thing, but it supplied what he needed for the time
being (if that makes sense) in the regex engine. Leo reckoned that
it looked okay, and promised to apply it if nobody hollered. He also
pointed out some problems with the current regex implementation to
do with reentrancy and memory leakage. It turns out that Steve was
working on languages/regex rather than the "rx_*" ops, which are the
ones that have the problems.
http://makeashorterlink.com/?P2FB16AB2
* Gregor N. Purdy had some problems with IMCC's syntax, a fragment of
code that he thought should work fell over in a heap. Both Mr.
Nobody and Leo pointed out that IMCC expects subroutines, and you
should wrap your code in a ".sub"/".end" pair.
Once Gregor had that straight he posted a Jako program and the IMCC
code he thought the Jako compiler should generate from it and asked
for any feedback before he went to change the compiler. Leo Tötsch
provided some (I assume) useful feedback.
A little later Gregor posted again, he was still having problems
with IMCC not quite behaving as he wanted for the Jako compiler. He
and Leo thrashed it out over a few messages and, to cut a long story
short, IMCC looks like it won't be changing. I'm not sure whether
Gregor is happy about this...
http://makeashorterlink.com/?X30C22AB2
http://makeashorterlink.com/?J51C32AB2
* Mr Nobody posted a patch to get IMCC to compile under windows.
Apparently the "OUT" label clashes with something in the windows
header files. The patch got applied.
* Gregor N. Purdy got a little confused by how IMCC generates PASM
code, and posted some sample code, interspersed with questions.
Which Leo answered. It's worth looking at this; it shows off the
kind of optimization that IMCC gets up to.
http://makeashorterlink.com/?E22C25AB2
http://makeashorterlink.com/?Y53C22AB2
PMCs are the thing
Dan announced that he's finally stopped waffling and frozen the PMC
structures `modulo the odd twiddling to it.' He's added a pmc.ops file,
and has started adding in ops to manipulate PMC internals. Leo asked for
some clarifications, got some, and then wondered what the final 'Parrot
Object' will look like.
http://makeashorterlink.com/?Z34C23AB2
"logical_not" issue
David Robins is having fun with "logical_not" and Ruby. The issue is
that *all* integers in Ruby are true, whether or not they are zero but
that with some of the assumptions in other PMCs. Robin offered 3
suggestions for how to fix it. Dan noted that it's an issue for Perl 6
too, since the truth or otherwise of a value can be modified by a
property of that value, coming up with a fix is on his todo list. David
wondered if this had been discussed before and offered another possible
way forward. Dan half liked the idea but noted that the approach didn't
work for "and", "or" and "xor", at least where Perl is concerned.
http://makeashorterlink.com/?A25C12AB2
The language that dare not speak its name.
After a fortnight during which nobody made any comment on Leon Brocard's
patch adding a brainfuck subdirectory to the languages directory,
Nicholas Clark committed it in CVS.
At which point Andy Dougherty spoke up to say he wasn't happy about it,
saying that he didn't wish to be associated with needlessly crude and
offensive language. After some further debate the subdirectory was
renamed to bf in such a way that, if you ask CVS it will tell you that
the brainfuck subdirectory does not exist now and never has existed.
Which seems strangely appropriate somehow. Fnord.
http://makeashorterlink.com/?K16C32AB2
http://makeashorterlink.com/?K16C32AB2
Parrot Organization
Michael Collins asked about the structure of the Parrot development
organization, and Dan provided some answers. My favourite Q&A:
Q. Is there any formal structure to this organization.
A. I [Dan] delude myself into thinking I'm more or less in charge....
http://makeashorterlink.com/?P27C63AB2
http://makeashorterlink.com/?P27C63AB2
Just when you thought it was safe
to start using long file names with impunity, Mr Nobody pointed out that
a bunch of the files in the parrot repository didn't play well with the
MS-DOS 'filesystem's 8.3 naming rules. "So what?" asked Aldo Calpini. Mr
Nobody asked if DOS was an intended compilation target. Answer: "No".
The consensus appears to be "Ha! We laugh at your crappy filename
restrictions and will not be jumping through any hoops to deal with a
faintly silly hypothetical target." Or maybe that's just my opinion
dressed up as consensus. Ah well, if I'm wrong I'm sure someone will
tell me.
http://makeashorterlink.com/?P38C21AB2
Meanwhile, over in perl6-language
The perl6-documentation team have been discussing String literals and
their discussion spilled over into perl6-language as there are several
things about them that are undefined and needed discussing by the
language crowd. It's all to do with how octal numbers and octal string
escapes are specified. Essentially, people don't like the current
Perl5/C style 0101 (octal number) and "\101" (octal string escape), so
James supplied a list of the other possibilities. (The current Numeric
literals doc say that "0c101" designates an octal numeric literal, but
then the consistent extension to string literals ("\c101" clashes with
the current method of specifying a control-char). After a certain amount
of debate Larry pulled one of his gloriously clear posts out of the bag,
sketching the issues and coming up with a straightforward and obvious
(but only with hindsight) way forward. It's good to be reminded why we
trust Larry. Anyway, it turns out that an octal number will be specified
using "0o101" and an octal character escape will probably be one of
"\0o[101]" or "\c[0o101]" (I like the second better...)
http://makeashorterlink.com/?V29C15AB2
http://makeashorterlink.com/?F2AC11AB2
Thinking about "\c[...]"
Once Larry had pulled "\c[0o101]" out of the bag, it fell to David Whipp
to wonder what you could get up to with it. For instance, could you do:
"print "\c[71, 101, 108, 108, 111]"" and have that print "Hello"? Damian
pointed out that Larry had already discussed some of this in Apocalypse
5, but that the separator character would probably be the semicolon.
Then Nicholas Clark got evil, and wondered about "\c[$(call_a_func())]",
but Damian seemed to think that wouldn't be such a good idea.
http://makeashorterlink.com/?T3BC23AB2
Purge: opposite of grep
Miko O'Sullivan suggested a "purge" command which would be to "grep" as
"unless" is to "if". Nobody seemed to like the name that much, though
most seemed to think the idea was sound. Michael Lazzaro suggested
"divvy" which would be used to break a list into multiple lists (he
initially proposed just breaking the list into two lists, but others
extended the idea to more). Damian didn't like the name, and initially
proposed "classify", which would return a list of array references.
Discussion continued for a while until Ralph Mellor suggested "part" as
the name for this putative function, which Damian leapt on with a glad
cry.
This went on for a while, with extra features being proposed and other
explorations of the possibilities including some rather nifty proposed
shorthand/DWIMmery.
Meanwhile Ken Fox wondered why we couldn't just implement
classify/part/divvy as a normal sub and wondered why everything had to
be built into the first version of Perl 6. So Damian implemented it, but
commented that "then the thousands of people who are apparently
clamouring for this functionality and who would have no hope of getting
the above correct, would have to pull in some module every time they
wanted to partition an array." Ken was impressed, and asked for some
commentary on how it all worked, which Damian provided. BTW, this code
is *really* worth looking at for an example of the kind of power that
Perl 6 will provide.
David Wheeler wasn't over keen on calling the function 'part' because
part has so many different possible interpretations. It turns out that
that's why Damian likes the name so much.
http://makeashorterlink.com/?D4CC52AB2
http://makeashorterlink.com/?J5DC16AB2 -- "classify"
http://makeashorterlink.com/?N2EC51AB2
http://makeashorterlink.com/?A1FC24AB2 -- Damian implements "part"
http://makeashorterlink.com/?G10D32AB2 -- Damian implements "part"
with sane formatting
http://makeashorterlink.com/?R12D21AB2 -- Damian explains it all
In defence of zero-indexed arrays
Michael G Schwern asked people to `Explain how having indexes in Perl 6
start at zero will benefit most users. Do not invoke legacy.'. Answers
ranged from the silly to the sincere. The best answer was "Because I
[Larry] like it" which, I think, trumps everyone.
http://makeashorterlink.com/?L23D26AB2
http://makeashorterlink.com/?J54D22AB2
Stringification of references
Joseph F. Ryan kicked off a discussion of the stringification of objects
and references and offered his suggestions. Joseph leans towards having
the default stringifications of objects and references provide
information useful to the programmer. I agree with him (so, if you spot
any bias in the upcoming summary that'd be because I'm biased). Michael
Lazzaro explicitly brought up the distinction between "stringification
for output" and "stringification for debugging", and came down in favour
of stringification for output (heck, he even wanted references to be
invisible to stringification). Piers Cawley told him he was very wrong
and appealed to the authority of Kent Beck (a Smalltalk and Java
programmer, possibly not the *best* authority to choose). Michael then
proposed a scheme involving subclasses of String, to provide cues for
different stringifications, which John Siracusa thought was going rather
a long way too far, coming down in favour of the "stringify for
debugging" position. I'm not sure anything has actually been *decided*
yet though. Tune in next week.
http://makeashorterlink.com/?O25D23AB2
Outline of class definitions in Perl 6
Simon Cozens asked for a translation of some Perl 5 style OO code into
Perl 6, and Luke Palmer had a go at the task, then Larry came through
with something a little more definitive (but not *actually* definitive
just yet, I get the feeling that a few things are still in flux...)
http://makeashorterlink.com/?W26D53AB2
http://makeashorterlink.com/?A57D24AB2
Perl 6 and Set Theory
Luke Palmer posted a fascinating document presenting a "new way of
thinking about some constructs." and proposed some changes to help with
consistency. The document covered junctions and classes, recasting them
as representations of finite and infinite sets. Only Damian responded
with a few corrections and clarifications noting that one of Luke's
proposed changes was rather fundamental, and that he wasn't sure he
wanted to make that change without some deep reflection (from someone)
on how that would affect the junction types that Luke hadn't considered.
Discussion continues.
http://makeashorterlink.com/?S68D21AB2
In Brief
Steve Fink is toying with adding OpenGL ops to Parrot.
Leon Brocard has used the native call interface features to add curses
support to Parrot and offered a version of life.pasm that makes use of
it.
The perl6-language crowd are currently working on string literals and
stringification.
Who's Who in Perl 6?
I'm bumping this one up the questionnaire queue slightly. I felt the
need for some controversy.
Who are you?
Abigail
What do you do for/with Perl 6?
Nothing, except for disliking languages that are white space
sensitive.
Where are you coming from?
I've been coding Perl since 1995. Joined p5p in 1996 or so.
When do you think Perl 6 will be released?
A usable release? Given the current rate in which apocalypses are
produced, I'd say 2008. Give or take a few years.
Why are you doing this?
I adore Perl. Perl5 that is. Programming in Perl5 is like exploring
a large medieval castle, surrounded by a dark, mysterious forest,
with something new and unexpected around each corner. There are
dragons to be conquered, maidens to be rescued, and holy grails to
be quested for. Lots of fun. Perl6 looks like a Louis-XVI castle and
garden to me. Straight, symmetric, and bright. There are wigs to be
powdered, minuets to be danced, all quite boring. I haven't been
impressed by new features yet, but I'm disappointed by what will be
lost.
You have 5 words. Describe yourself.
My mind is twisted. Backwards.
Do you have anything to declare?
One of the great things about Perl5 is that I don't have to declare
anything I don't want to.
Acknowledgements
Another week of writing on the train and, for a change of scenery, at my
parents' house, fuelled, as usual by large amounts of tea.
Proofreading was once again down to Aspell and me. Any errors this week
are probably my fault, it's about time I started accepting my
responsibilities.
Thanks to everyone who has sent me questionnaire answers, I've got a
queue of about four left so, if you work with Perl 6 (or, like Abigail,
hate it) please answer the same set of questions Abigail just answered
and send them to me at <mailto:[EMAIL PROTECTED]>. Thanks.
I got some mail last week from someone praising me for the summaries
(thanks), but wanting to know how he could contribute his time and
energy, so this week the chorus has a few extra lines in it:
If you didn't like the summary, what are you doing still reading it? If
you did like it, please consider one or more of the following options:
* Send money to the Perl Foundation at
http://donate/perl-foundation.org/ and help support the ongoing
development of Perl 6.
* Get involved with the Perl 6 process. The mailing lists are open to
everyone, http://dev.perl.org/perl6/ and
http://dev.perl.org/parrot/ are good starting points with links to
the appropriate mailing lists.
* Send feedback, flames, money and or lucrative employment in the
Doncaster area to <mailto:[EMAIL PROTECTED]> (No, I'm not
unemployed at the moment, I just want to work nearer to home...)
The fee paid for publication of these summaries on perl.com is paid
directly to the Perl Foundation.
--
Piers
"It is a truth universally acknowledged that a language in
possession of a rich syntax must be in need of a rewrite."
-- Jane Austen?
