The Perl 6 Summary for the Week Ending 20020915
Happy birthday to me!
Happy birthday to me!
Happy birthday dear meeeee!
Happy birthday to me!
And, with a single breech of copyright, Piers was free. The production
of this summary was delayed by my turning 35 on the 15th and then
spending the Monday train journey reading one of my birthday presents
(*Dead Air* by Iain Banks, it's jolly good) instead of writing a
summary. So this morning I left the book at home.
So, what's been going on with Perl 6. We'll start, as usual with
perl6-internals.
Goal call for 0.0.9
The week before, Dan had asked for some suggestions as to what should be
the priorities for the 0.0.9 release of Parrot. One of Nicholas Clark's
goals from last week was the `Careful elimination of all compiler
warnings, particularly on non x86 platforms, and for builds with
non-default INTVAL size', and discussions of how to go about doing this
(and indeed some doing) carried on into this week. There was also some
discussion about whether IMCC and the Perl 6 compiler should be built by
default. On the one hand, it would mean that the tinderboxes were
testing those important subsystems, on the other hand, it was thought
that there were some people who wouldn't be interested in testing those
things. Consensus seemed to be that we should just build and test them
anyway.
http://makeashorterlink.com/?M2E0225D1
Scheme Implementation Details
Jürgen Bömmels and Piers Cawley continued their discussion of how to go
about implementing a scheme interpreter, and "lambda" in particular.
Piers made noises about a proof of concept implementation of Scheme that
he'd made using Perl objects, but didn't show code. (And, I can
exclusively reveal, will not be showing (the original) code owing to
badness with backups and lackadaisical use of CVS). Jürgen, who had
actually made the effort of writing some code, listened politely and
agreed that Piers' suggestions looked like they might be a way forward.
Jürgen went away and implemented a first cut at "quote", "define" and
"set!".
http://makeashorterlink.com/?O2F0325D1
http://makeashorterlink.com/?K101255D1
"chr", "ord" etc.
Clinton A Pierce restarted this thread and discussed what he'd like to
see (apart from a pony) from Parrot's equivalent of Perl 5's "pack".
Clint wondered whether Parrot "pack" should use a template, or if it
should be implemented as a horde of smaller ops, each handling a
different conversion, so that a single, Perl level call to pack would
become lots of op calls at the parrot level. Clint also drools at the
thought of doing "sprintf" at the parrot level. Aaron Sherman agreed
with most (all?) of Clint's proposals, and also wants a pony. (Who
doesn't?). Peter Gibbs went so far as to offer a patch which implemented
a subset of pack functionality, and was applauded. Graham Barr wondered
if pack should also allow for packing to 'native' types, which wouldn't
have to worry about endian issues. Peter thought that would be a good
idea. Nicholas Clark pointed out that extending the code to cope with
unsigned integers would be a good idea too.
http://makeashorterlink.com/?A311215D1
Lexicals
Jürgen Bömmels asked a pile of questions about the implementation of
lexical variables and how one could use them to make a closure. Jonathan
Sillito provided a mixture of answers and guesses. It seems that we're
waiting on Dan to firm some things up about lexicals.
http://makeashorterlink.com/?E221215D1
IMCC 0.0.9 Runs 100% Perl 6 Tests + Various Results
Leopold Toetsch has been working on getting IMCC to generate parrot
bytecode directly rather than going through a stage of generating an
intermediate ".pasm" file, and had been having some problems with
`writing out the .pbc, especially Const_Table, type PFC_KEY /
PARROT_ARG_SC'. Two hours later he announced that he had all the perl6
tests running successfully within IMCC, but only if GC was turned off
(there are problems with the longer running tests when GC is turned on).
Things get progressively worse as first JIT, and then Predereferencing
are turned on.
Dan wondered what the GC bug could be. Leo wasn't sure but posted some
possible pointers. Peter Gibbs thought that at least one of the bugs was
in continuation.pmc and posted a patch which fixed one of the problems
when running under parrot. Meanwhile Leo tracked down the bug to a bit
of code that he'd appropriated from debug.c, so he fixed his IMCC and
sent in a patch to fix debug.c as well. Applying both patches meant that
the tests all passed under both IMCC and parrot.
Dan applied both patches.
Leo later fixed his problem with writing out a .pbc file directly from
IMCC, and offered a patch to packout.c which he described as ugly, but
working.
I think Mr Toetsch is going go get my 'kudos' award for this week as he
later patched things to make the 'predereferenced' run mode work again
(all perl6 tests pass when run with -P). By the way, there appears to be
no reference to 'predereferenced' in the glossary.
http://makeashorterlink.com/?R241515D1 -- Problem
http://makeashorterlink.com/?V551125D1 -- Qualified success
http://makeashorterlink.com/?H261615D1
Problem Parsing Builtins
Aaron Sherman and others have been torture testing the Perl 6 compiler.
The most comprehensive test is the Builtins.p6m file (now split into
several smaller files) which provides prototypes (and a smaller number
of implementations) for Perl 5's built in functions (we don't know what
Perl 6's builtins will be, so Perl 5 is a good start). Sadly, right now
the Perl6 compiler can't cope with all the builtins, so there's been a
game of working out which is broken, the parser, or the code. Aaron has
posted many short scripts highlighting problems he's found. My
particular `favourite' is "my $x = 1; $x = +x" sending the compiler off
into an infinite recursion. Sean O'Rourke has added these issues to his
queue.
[RFC] buildings core.ops op_hash at runtime
Leopold Toetsch posted a proposal for altering the build system to get
rid of some rather over the top duplication of (generated) code.
Nicholas Clark liked the idea, but I don't believe the patch got
applied. Yet.
Leo also suggested moving the op_info_table out into a separate file
which could be shared by the various core_ops*.c files.
http://makeashorterlink.com/?C171325D1
http://makeashorterlink.com/?I181315D1
IMCC / Mac OS X problem
Leon Brocard (yay! Still batting 100% on this one...) has been having
problems building IMCC under Mac OS X. The individual .c files all
compile, but bad things happen at link time. Leo, Kevin Falcone, and
Andy Dougherty all pitched in and, after a flurry of patches, IMCC is
now building and working correctly under Mac OS X.
http://makeashorterlink.com/?R591215D1
Problems with 64 bit integer builds
There have been problems building Parrot on some of the tinderbox
systems, and many boxes are not green. Andy Dougherty had some thoughts
on this, and on how to improve things. Andy's view is that so many of
the tinderboxes are broken, it's hard to tell whether your new patch is
making things better or worse, especially when the rebuilds can take
several hours in some cases. Andy hopes that, once the majority of boxes
are green most of the time, people will take more notice when one or
another turns orange or red. In another thread, Andy offered a patch
which had been a showstopper for some architectures, which would dump
core during config's alignment detection tests.
http://makeashorterlink.com/?Q1A1235D1
http://makeashorterlink.com/?Z6B1335D1
RFC: How are compound keys with a PerlHash intended to work?
Leopold Toetsch wondered about the handling of compound keys in PerlHash
objects. Dan confirmed that Leo's intuition about this was right, which
was good, because Leo had a patch ready, but he still wondered about a
some additional vtable methods. So he made some more proposals about how
to deal with that case. Dan again agreed with Leo's analysis, and Leo
came up with another patch. Steve Fink apologised for not having done
this already but his `tuit shipment was confiscated due to heightened
airport security.' Steve also neatly summarized the conclusions reached
last time this came up.
Meanwhile, Graham Barr wondered where any type checking would happen.
Leo thought it was implicit on lookup and showed code. So did Dan, but
Ken Fox is still unsure.
http://makeashorterlink.com/?P2C1325D1
http://makeashorterlink.com/?N2D1625D1 -- Leo's patch
http://makeashorterlink.com/?I1E1215D1
Meanwhile, in perl6-language
The week before, Erik Steven Harrison had wondered what counted as a
runtime property, apart from "true" and "false". This week Damian popped
up with a list of ten off the top of his head. "return 255 but undef;",
or "$name = "Damian" but We_better_call_ya("Bruce")" anyone?
http://makeashorterlink.com/?F2F1125D1
Second try: Builtins
Aaron Sherman's efforts at producing an initial builtins list for Perl 6
got discussed on the language list as well. Chuck Kulchar had wondered
how well, if at all, they worked with the current perl6 compiler (they
don't... yet), and why they were written in Perl. Aaron Sherman posted
his reasons (maintainability, maintainability and maintainability).
Nicholas Clark argued that Parrot code wasn't necessarily hard to
maintain, and also made the case for implementing some functionality in
C. Aaron thought that, eventually, they're be a mix of different
implementation languages, with many of the `munge args, call equivalent
library function' type functions moved out into libraries anyway.
http://makeashorterlink.com/?N202515D1
More A5/E5 questions
Discussions of the Perl 6 rules system rolled on. David Helgason had
worries about hypothetical variables but keys in a hash and should not
therefore have sigils in their names at all. Damian pointed out that
*all* Perl 6 variables were just keys in a hash. David wondered about
the difference between binding a value to a variable in a containing
scope and just binding to an entry in the match object (Damian and
Allison apparently have a really neat idea for this, but it's not yet
had the Larry stamp of approval). David's last worry was that $0 was a
rather cryptic name for the match object and shouldn't it have a
meaningful name like $MATCH (Damian thought that squashing a cryptic
name in favour of an arbitrary one wasn't necessarily a win.
Jonathan Scott Duff had wondered (in off list mail to Damian, but Damian
answered in public) how he could tell "^^" and $$ only to match just
after and before his platform specific newline sequence. Damian thought
that suggested rolling ones own "<sol>" and "<eol>" rules. Jonathan had
also wondered about some of the the binding semantics of nested rules.
Damian's answer gave him an appropriate `ah! yes!' moment.
Aaron Sherman had another question about rules and kicked off the
`Throwing lexicals' (Weren't they a band?) by wondering `How do rules
create hypotheticals?' Everyone passed up the chance to do a `Well, a
mummy rule, and a daddy rule, who are very much in love...' joke,
leaving it to the summary writer.
I confess, I'm not sure I understand Aaron's concern (about what to do
when you assign to a hypothetical that doesn't exist in a containing
scope. I thought you just bound to an appropriately named key in the
current match object), which makes things a tad tricky, but Luke Palmer
seemed to understand and wondered if there would be some way of
declaring that a given hypothetical *wouldn't* infect its containing
scope(s). Damian popped up again, promising that, once Larry had made a
decision, he would be unveiling one of the solutions that he and Allison
have cooked up.
http://makeashorterlink.com/?H312525D1
http://makeashorterlink.com/?W122245D1
http://makeashorterlink.com/?F232265D1
Blocks and semicolons
Piers Cawley wondered about blocks, statements and when they need
terminating semicolons, and kicked off a long thread. To be honest, I'm
not sure it really went anywhere, but we covered a lot of ground. The
confusion arises, I think, because the design of Perl6 has moved (rather
substantially in places) from the design described in some of the
earlier apocalypses and exegeses. Questions like `is "when" a statement,
or just a clever function?', `has Larry changed his mind about no
special cases for blocks?' and others would appear to be standing in
need of some definitive answers. These will, of course be forthcoming,
if only in Perl6's final grammar, but we're an impatient lot.
http://makeashorterlink.com/?L242565D1
XS in Perl 6
Aaron Sherman had a few thoughts about XS (well, whatever is going to
replace it in Perl 6 and Parrot anyway) which he shared with the list.
Essentially his proposals covered ways in which modules that are
partially implemented in other languages could be cleanly declared and
prototyped using Perl syntax rather than the current method involving
XS, which looks like no other language on ghod's green earth. Brent Dax
proposed a slightly different syntax, using a "returns" property ("sub
foo is returns(...)"? Don't you love grammar?). The thread got rather
long as Brent and Aaron discussed things back and forth, with Nicholas
Clark interjecting at one point to draw the participants attention to
the fact that they seemed to be on the verge of reinventing Inline::C.
Tim Bunch suggested that we `should be thinking about the forward
declaration syntax and semantics for using existing libraries at this
stage. [He suspects] that it'll then become clear how to add extra code
in a simple and natural way.'
Tim also pitched in with a long quote from Larry about his goals for the
Perl 6 extension mechanism.
David Whipp wondered if we shouldn't actually be thinking about
*Parrot's* XS replacement rather than Perl 6's. Aaron thought not,
because even when parrot's extension model was fully specced out, we
still need to worry about how that interacts with Perl at a language
level. Dan Sugalski disagreed with Aaron, pointing out that Perl 6 XS
isn't due to be dealt with until Apocalypse 21. Aaron wondered if this
*really* meant we'd be waiting for `16 more Apocalypses before we write
code that allows "chdir()" to call the C library function?' Dan thought
Aaron was worrying unduly and pointed out that "chdir" is, or will be, a
Parrot opcode. Aaron responded to this by stepping back and defining
some useful terms and stated his current position in those terms. And
then the week ran out.
This one could run and run. Tune in next week for the exciting
continuation. (Ooh, we haven't done continuations recently have we?)
http://makeashorterlink.com/?I252215D1
http://makeashorterlink.com/?Q462215D1
http://makeashorterlink.com/?C272115D1
http://makeashorterlink.com/?W482235D1
Passing arguments
In a subthread of the `blocks and semicolons' thread, Aaron Sherman
wondered about passing arguments. Aaron listed five different forms of
and wondered about how one would mix up the different styles. Luke
Palmer and Brent Dax both wondered what made one of his special cases a
special case. Again, it looks like the whole area of prototypes could
use some cleaning up (but then we're currently working on clues from
other design documents; hopefully the upcoming Apocalypse 6 will clear
up many of these issues).
http://makeashorterlink.com/?N392225D1
In Brief
Steve Fink committed his IntList patch, and Josef Höök queried the
creation of an intlist.c file in the parrot core, as his matrix patch
had been rejected for doing something similar. Nobody has responded to
this yet...
Ramesh Ananthakrishnan wondered whether compiling C down to Parrot would
be a useful thing to do, as a way of magically porting useful stuff that
was already written in C. Aaron Sherman thought that it wouldn't be
useful as a 'magic porting' tool, as that would be better done by
linking to existing C libraries, and that for small fragments, a manual
conversion would probably be better anyway.
Ramesh (or should that be Ananthakrishnan) also wondered if it is
possible to write networking code in parrot. Answer, not yet, but a
Sockets extension is almost bound to get written at some point.
Andy Dougherty patched the build's link order to take traditional, order
dependent, linkers into account.
Jerome Quelin fixed Befunge (though, with a language like that, how
anyone could tell it's broken is a mystery) to use the new "chr" opcode.
Dan Sugalski turned 35 on the 12th. I turned 35 on the 15th. Did I miss
anyone else's birthday?
Leopold Toetsch patched "Parrot_vsprintf_s" and after prompting supplied
a test which failed without the patch in place. (Remember boys and
girls, if you're offering a patch that fixes a bug, make sure you also
supply a test that shows up the bug.)
Jeff Forr wanted to declare next (this) week to be a week of bug
hunting, but Nicholas Clark pointed out that this clashed with
YAPC::Europe and maybe it was better to make the week after a bug hunt.
Jeff agreed.
The Perl 6 Mini Conference in Zurich
Also going on last week was a Perl 6 mini conference, held in Zurich.
Larry, Damian, Dan, Allison and Hugo all gathered to sit round a table
and thrash out some more of the Perl 6 design. I assume that whiteboards
were also available. As well as doing design work, there was a mini
conference, complete with talks from all of the above, and due to time
and money commitments I couldn't make it. However, Paul Johnson could,
and he wrote me a report, which I present here pretty much unedited.
A Report, by Paul Johnson
Last week, Perl 6 moved to Zürich. The bulk of the Perl 6 design team
was here as guests of ETH, and spent the week, er, designing Perl 6 I
suppose. But maybe they were out exploring Zürich and its environs. If
they were, who can blame them? If they weren't, well they'll just have
to came back another time :-)
On Thursday and Friday they also managed to fit in a Mini::Conference on
Perl 6. In attendance were Larry Wall, with his wife, Gloria, Damian
Conway, Dan Sugalski, Allison Randall and Hugo van der Sanden.
We were treated to two days of talks and discussion about Perl 6. Larry
Wall gave the keynote speech to start the conference. As always, Larry's
talk was interesting and entertaining. The scheduled topic was "Studies
in the Ballistic Arts", however, Larry said that this title was prepared
before the talk itself, and the talk, along with the title, morphed into
one about the Science of Perl. This will be heard again at YAPC::E in a
few days, and so I won't spoil it by attempting to summarise it here.
Next up was Damian Conway, who gave his presentation entitled
"Introduction to Perl 6", covering the first five Apocalypses. Damian
has managed to acquire quite a reputation within the Perl community, and
Larry promised that Damian would be more entertaining than he. That was
quite a promise, but I don't think anyone was disappointed. Damian in
turn promised that Dan, speaking next, would be more entertaining than
he. I think Dan was probably too busy to notice, checking in some
patches or redoing the GC or something.
Damian noted that the audience was probably more sympathetic than most
he gave the presentation to, given that they had come to a two day
conference devoted to Perl 6. There were nonetheless a number of people
who were worried about the move to Perl 6, and one who was still worried
about moving to Perl 5! I think that most of Damian's jokes flew high
over the heads of most people, but I appreciated them at least. I
suppose that XXXX (4x) hasn't made it to Switzerland. And maybe
Crocodile Dundee wasn't such a big hit. Even Switzerland's joining of
the UN two days earlier seemed to go unnoticed, although it is UNO here.
I think there were a few Java programmers in the audience too, since
when Damian mentioned about Java having a HelloWorld library about half
the audience laughed and half seemed a little concerned that they hadn't
heard of it before. And the suggestion that Archbishop Tutu might not
like being interpolated was entirely missed. (Should we interpolate $to
too?) Still, had the jokes been in German, they'd have flown right past
me instead. And I trust Damian's German accent will stay in place should
he have occasion to talk about B&D languages in Munich.
Unsurprisingly, Dan spoke about "The Parrot Virtual Machine". Dan
actually gave two presentations back to back. The first was an overview
of Parrot, and the second was a more detailed look at parts of it. This
was a very interesting look at the fast moving world of perl6-internals
and seemed to be well received by a knowledgeable audience.
The second day started with a presentation by Allison Randall entitled
"Linguistic Basis of Perl 6". Every so often, in perl6-language in
particular, some discussion about linguistics crops up, often referring
to tagmemics. Allison explained to us what a tagmeme is, and how it
relates to the design of Perl 6. I won't pretend to understand it all,
but apparently tagmemics is the Swiss Army Knife of linguistics, a
tagmeme is a unit in context, tagmemes are fractal, and both "etic" and
"emic" are real words, protestations of my spell checker to the contrary
notwithstanding. I understand that Allison gave this talk at TPC and
will also give it at YAPC::E, so soon we'll all understand tagmemic
matrices and be perfectly happy to get dropped off into some uncharted
jungle.
Following Allison's presentation there were questions about some minor
syntactic issues such as why the switch statement used "given" and
"when" instead of "switch" and "case". The explanation of how nicely it
read in English was countered with arguments that that wouldn't benefit
the German speakers so much and that "switch" and "case" were probably
already familiar to programmers. Damian suggested that maybe a German
Perl grammar would be in order, to which the inevitable response was
that a Swiss German grammar was really required, but which dialect would
it be in? Damian showed how easy it would be to derive your own Perl
grammar and change keywords if you didn't like them. This was also
useful to the chap who wanted elsif spelt correctly.
Damian's second presentation was "Programming in Perl 6" in which he
took a number of real Perl 5 programs written and regularly used by
prominent members of the Perl community, and he changed them into Perl
6. He did this twice, first to produce a minimal delta change and second
to produce idiomatic Perl 6, at least insofar as Perl 6 has managed to
acquire idioms. Both of Damian's presentations were punctuated with
questions to Larry, asking if what Damian had just presented was true
this week too. In some cases the language design seemed to be taking
place before our eyes.
This presentation seemed to allay a lot of fears and everyone seemed
quite happy with Perl 6 to the extent that Damian finished half an hour
early. The option was a long lunch or Damian offered to give his
Lingua::Romana::Perligata presentation. I don't think there was ever any
doubt, but when Larry mentioned that he had never heard that talk it was
decided. The talk is normally two hours long, but Damian managed to
squeeze it into 45 minutes. I think this was probably aided in part by
most people simultaneously missing the jokes and being comfortable with
a language which requires the matching of number, case and gender. I
suspect this is the opposite from most native English speaking
audiences.
Finally Hugo was here representing the face of sanity. He told us of his
plans for Perl 5.10. These included making perl clean, small and fast.
To this end he intends to rewrite parts of the regular expression
engine, to oversee the creation of a scheme whereby there are multiple
blessed perl installations, and to claw back some of the speed that has
been lost since version 5 was released. In short, to ensure that making
Perl 6 better, faster and stronger than Perl 5 is as difficult as
possible.
Last on the agenda was a question and answer session with the entire
team. This was especially interesting, in part I think because there was
not an enormous number of questions. This allowed the answers to be
complete, to the point of verging on rambling. That's not a bad thing,
because it let us get past the superficial answers and into more
philosophical areas. Dan told us why Parrot was called Parrot. Larry
told us why Perl was called Perl, what it stood for and when, and why it
was perfect for search engines even before there were search engines.
Dan told us not to get worried about everything, after all, it's only
ones and zeros. Damian and Dan alluded to interesting things they could
tell us, but then they would have to shoot us. Larry speculated on
whether placing a time bomb in the perl interpreter would help us find
out who is using Perl and for what. Larry and Damian told us some scary
things that people do with Perl and Larry told us he flew over here in
one of them. Larry also told us the secret of leadership (which is at
least 2000 years old), and talked about how well his goal for the
community's rewrite of the community is working. And there was a bunch
of other stuff that I was far too busy enjoying to make notes about.
All in all, it was a thoroughly enjoyable and informative couple of
days. Many thanks to ETH Zürich and in particular to David Schweikert
for organising the event. Attendance was about 90, and profits, which
look to be around CHF 4000 or so go the the Perl Foundation. Next stop:
Münich.
Who's Who in Perl 6
You lucky people, last week you got Dan, this week it's Damian. Next
week the World! Bwah hah hah ha! Ahem. Without further ado:
Who are you?
Damian Conway
What do you do for Perl 6?
* I help Larry with the design of the language syntax and semantics
* I write the Exegeses (which explicate Larry's Apocalyptic designs)
* I create Perl 5 modules to prototype and demonstrate Perl 6 features
* I roam the worlds -- both real and virtual -- explaining Perl 6
Where are you coming from?
Two years of Electrical Engineering degree, four years of Computer
Science degree, six years of PhD research, eight years of designing
programming languages, two decades of teaching programming, an
abiding interest in human-computer interaction, a deep scepticism of
formal/theoretical solutions to practical problems, an abiding
belief that computers and languages were meant to serve humans not
vice-versa, and the overriding axiom that simpler is better (or, at
least, simpler).
When do you think Perl 6 will be released?
By Christmas.
Why are you doing this?
I'd been doing language design for the better part of a decade
before I started using Perl. So when the opportunity arose to work
on my favourite language and collaborate with such an
extraordinarily talented team of people, how could I possibly
resist?
You have 17 syllables. Describe yourself.
Out of the torrent
an excited voice describes
the passing wonders.
Do you have anything to declare?
You're kidding, right? *How* many hours do you have?
Acknowledgements etc.
You may have noticed that I'm a little late mailing the summary out this
week (though if you read this at www.perl.com you're probably wondering
what I'm on about). Things have been hectic, and I really can't type or
think fast enough. Normal service will hopefully be resumed this week.
Thanks are due to Damian for making the time to answer the
questionnaire, even if he did cheat on the `five words' question. Thanks
are also due to everyone who has taken the time to send me answers over
the weeks, apologies for not thanking you immediately. As usual, If
you're involved on either of the main Perl 6 development lists, please
consider answering the questions and sending your answers to
<[EMAIL PROTECTED]>. I'm running low on answers, and I'd really
like to see responses from (among others) Leopold Toetsch, Steve Fink,
Brent Dax, and Jeff Goff. I don't *care* if you've already answered
Bryan Warnock's questions, it's a different summary now.
Thanks too to the crack team of proofreaders from the rhizomatic.net irc
server who will hopefully have whipped my grammar into shape by the time
I think `I really should get my finger out and post this'.
As usual, if you think that this summary has value, please consider
sending money to the Perl Foundation http://donate.perl-foundation.org
and help to support the ongoing development of Perl. The O'Reilly
Network will, as usual, be paying my publication fee for this article
directly to the Perl Foundation. If you didn't like the summary, write
your own; different viewpoints are always welcome.
If you want to reward me directly, well, iBooks are always nice (but I'd
be *so* embarrassed if I received one), but so is feedback. Let me know
what you think.
--
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?
