The Perl 6 Summary for the week ending 20021103
Welcome to the latest of the ongoing series of Perl 6 summaries, in
which your arrogant moderator does battle with the forces of prolixity
in a Brobdingnagian attempt to tame the tortuously tangled threads of
Perl 6's design and development mailing lists. And if I keep up the
purple prose at that rate it'll *still* be clearer than the tangle that
is this week's perl6-language discussion.
However, because it's customary, and because the language list scares
me, we'll start with the comparatively tame perl6-internals.
Fun with file formats
Toward the end of last week, Rhys Weatherley had asked about being able
to insert arbitrary chunks of metadata into parrot bytecode files. Dan
ended up producing a `draft sketch' of the bytecode generation
facilities and the ability to add arbitrary chunks of metadata was
conspicuous by its absence. People didn't seem to be happy about this,
lamenting a lack of flexibility, both in the overall file structure and
in what one could stick into the bytecode. Dan mounted a sturdy defence,
pointing out that we want `a file format that does what we need it
to--present executable bytecode data to the interpreter--as fast as
possible. Everything else is secondary to that.'
Kv Org wondered if it would be a good idea to worry about sandbox issues
in the bytecode format, but nothing came of that question. Well, not
this week anyway.
http://makeashorterlink.com/?S1F442C52
http://makeashorterlink.com/?V20551C52
http://makeashorterlink.com/?H21513C52
http://makeashorterlink.com/?H22541C52
Portable linking issues
Andy Dougherty is having portability problems. He wants to portably
compile and link 3 files and he wondered what was the best to get an
early test compiled properly on all platforms. Help was supplied, the
build was fixed, and the world remained safe for democracy. (Modulo a
few local difficulties.)
http://makeashorterlink.com/?Q23532C52
Implicit stack direction probe
Meanwhile, Jason Gloudon's patch to move the stack direction probe back
to initialization time rather that compile time was offered. I'm
assuming that Nicholas Clark's suggested speedup trick from last week
was implemented as part of it, but I'm no great understander of C.
http://makeashorterlink.com/?R54532C52
Of MOPS and Microops
There's been some discussion of granting a small number of Parrot
registered 'most favoured' status. The idea being that a small number of
registers would actually be held in global (possibly real register)
variables, with the rest being accessed through via indirection through
the interpreter. Apparently the JIT core already does some optimization
along these lines, and Dan doesn't seem to be sure that doing it for the
main interpreter would actually be much of win. Discussion continues.
http://makeashorterlink.com/?L55521C52
Very complete lexical scopes
Jonathan Sillito has submitted a patch which `implements a very complete
set of lexical scope semantics'. It looks pretty cool to my untutored
eye. General response was positive, though Jürgen Bömmels did have a
query about how to create a new scope.
http://makeashorterlink.com/?W26514C52
miniparrot, a first attempt
If you've been paying attention to the Parrot build process, you'll be
aware that it was always a goal to use a cut down variant of parrot
itself to run the configuration tests. The plan is that this miniparrot
should be buildable with nothing more than an ANSI compliant C compiler.
Josh Wilmes thinks we're about ready to start building said miniparrot,
and offered his first cut to the list. Response was positive, with
quibbles, which is about what one would expect.
http://makeashorterlink.com/?W37512C52
Meanwhile, over in perl6-language (or "The Horror! The Horror!")
The dreaded `Operator Reshuffle' thread continues apace -- of the 450
posts last week I'd say about 400 of 'em were discussing various aspects
of this. Bear in mind too that the path of discussion could be described
as helical (sort of like circular, but getting more and more wound up
with each go 'round). There are at least two factions involved, roughly
caricatured as `Simon Cozens vs. The Rest of the World'. Simon can be
thought of as the voice of conservatism (or Reason, depending on whether
you agree with him or not), generally arguing against stuff he considers
massively ugly or confusing. Simon's allies vary depending on which
issue he's discussing and his worries include:
* Perl 6 is going to be even harder to parse than Perl 5
* Unicode operators in the core language are Just Wrong. Lots of
people agree with him on this.
* Superpositional operators will be too rare to justify giving them
precious one character operators.
This is, of course, a gross simplification of what's going on in the
various operator threads, but it does cover a fair number of the issues
that are arising in the attempt to get "^" back as exclusive or (which
then frees "~" up to become string concatenate, which... ah, go read
last week's summary, I already did this...)
BTW, `Vectorizing' is the new `Hyperizing' (or did I do that last week?)
Here's the various threads involved in the kerfuffle, along with Michael
Lazzaro's utterly wonderful summaries of the current core operator list
as he sees it.
http://makeashorterlink.com/?R26F21E42 -- Op list, Take 3.
http://makeashorterlink.com/?L28532C52 -- Take 4
http://makeashorterlink.com/?B69511C52 -- Take 5
http://makeashorterlink.com/?U1A561C52 -- Take 5a
http://makeashorterlink.com/?U2B553C52 -- Take 5b
http://makeashorterlink.com/?S5C542C52 -- Take 6
http://makeashorterlink.com/?O2D522C52 -- Pointers to Unicode stuff
http://makeashorterlink.com/?C5E522C52 -- Someone coming in late
http://makeashorterlink.com/?L2F542C52 -- Questioning the value of
infix superpositions
Smalltalk type collection classes?
One of the subthreads of the mammoth operator thread covered whether it
might be a good idea to include a set of Collection classes in the style
of the Smalltalk Collection hierarchy to the Perl 6 core dist.
http://makeashorterlink.com/?H40652C52
Persistence of superpositions
Buddha Buck wondered how pervasive superpositions were, and for how long
they would remain entangled. Damian thinks they should be all pervading
and fully propagating. This thread didn't really stay very on topic...
http://makeashorterlink.com/?K61613C52
Proposal: Vector operators for Hashes
Arcadi made some proposals about how to extend the concept of vector
operators to Hashes as well as lists and arrays. Discussion ensued.
People seem to like the idea of extending vector ops to cover hashes,
but weren't necessarily sure that Arcadi's approach was the right one.
'Adverbial' control of how the vector ops work was also discussed,
though Larry gave the impression that he thought this might be a
generalization too far...
http://makeashorterlink.com/?K12623C52
Plaintive whine about "for" syntax
Dave Storrs really doesn't like the syntax of the `parallel streams'
variant of "for":
# This iterates over @a and @b in parallel
for @a; @b -> $x is rw; $y { $x = $y[5] }
and he offered a list of suggestions, though I think more people
disliked his alternatives (even among those who didn't like the current
syntax) than liked 'em. Damian pointed out that a little finesse with
the editor could be of some assistance:
for @a ; @b
-> $x is rw; $y { ... }
Ed Peshko wondered what happened when you had a lot of parallel streams,
and Damian obliged with:
for @a; @b; @c; @d; @e
-> $a_var1 is rw, $a_var2 is rw;
$b_var is rw;
$c_var is rw;
$d_var is rw;
$e_var1 is rw, $e_var2 is rw
{
...
}
But this is a somewhat pathological case. Damian also mentioned that he
and Larry had thought long and hard about whether or not to interleave
sources and iterators before deciding on the current syntax.
http://makeashorterlink.com/?W23612C52
http://makeashorterlink.com/?Y54632C52
Nondeterministic algorithms, flexops, and stuff
Piers Cawley made heads hurt (his included) when he posted a question
about using superpositions (aka flexops) to implement non deterministic
algorithms. The particular example given was an algorithm to find a path
between two nodes of an acyclic directed graph (lifted from a text on
lisp). Jonathan Scott Duff thought the idea was 'neat'. For an encore,
Piers redid the function without flexops, using a continuation based
implementation of "choose" and "fail" (which hurts my head more than the
superposition based version, frankly).
http://makeashorterlink.com/?E55625C52
Primitive Boolean type?
Michael Lazzaro asked a tricky question, can a "bit" be undefined? If
so, then it leads to the somewhat counterintuitive assumption that one
would need two bits to store a single `bit'. Which is certainly odd.
However, it turns out that native types like "bit", "int", etc cannot be
undefined, so that's all right. This then branched off into a discussion
of whether Perl 6 would have an explicit Boolean type. It won't. Unless
Larry changes his mind.
http://makeashorterlink.com/?J66625C52
Labelled if blocks
Last week, Steve Canfield wondered if Perl 6 would have labelled if
blocks, which would allow one to jump out of arbitrary levels of nested
ifs. It seems the answer is `no', but this led to a discussion of
possible control statements which affect the flow of control in
different sorts of blocks (subs, conditionals, loops, etc.). It's
looking like we may end up with a "leave" statement. The other
possibility would be to make return a method, allowing one to do:
Loop.return($x)
or whatever.
http://makeashorterlink.com/?I17625C52
http://makeashorterlink.com/?J28614C52
In Brief
There was some discussion on the internals list about what functions
need to have an interpreter argument. The basic rule appears to be `if
it's going to allocate memory, it needs an interpreter'.
Leopold Toetsch has rejigged the startup procedure so that we will
always have a valid interpreter, making patches like the one that
allowed for a NULL interpreter in "sprintf" unnecessary.
Discussion of the Parrot Copyright/License changes was subdued,
bordering on the nonexistent. Lets hope it stays as smooth.
Leo Toetsch has been doing various refactorings of Parrot ops.
There was discussion about how to generate the MD5 hashes for parrot
bytecode `fingerprints'. The catch is that the Perl module Digest::MD5
isn't guaranteed to be available on all Perl installations...
Josh Wilmes did a massive 'indentation clean up' patch (2000+ line
patch).
Allison Randal has a fascinating article all about Perl 6 topics and
topicalizers at http://makeashorterlink.com/?W59612C52, which is well
worth the read.
Paul Johnson had some thoughts about using properties on statements and
the like as a way of providing metadata to things like code coverage
tools.
Leon Brocard is on Holiday.
Who's Who in Perl 6?
Who are you?
Mike Lazzaro. My wife and I own a company called Cognitivity
(http://www.cognitivity.com/) in Burbank, California -- we met at
Caltech, in Pasadena. We use Perl5 for our commercial e-learning
software (online, customizable corporate training software). This is
the first company we actually own, after working as
consultants/contractors/employees for years at other places. It's
great.
What do you do for/with Perl 6?
Originally, I just wanted to document Perl6's OO behaviours, but I
soon found that to be impossible without documenting everything else
first, so that's what I'm doing. I'm going piece-by-piece through
all the early Apocalypses, attempting to fill in all the details and
implications, which I am writing up in book-like form. As I get them
done, I'll post them for review and feedback -- but before that,
I'll have a lot of little questions and inconsistencies that I need
to pin down.
My feeling is, because I'm *not* on the design team, and I *don't*
know all the thinking on how and why things are decided, I'm a good
test person to write newbie-level documentation. If you can explain
it to me, that's a pretty good indication that you and I can explain
it to someone else. I think the disconnection between designer and
documenter will be important, in this case, because we want Perl6 to
be heavily adopted by mere mortals, not just experts.
Where are you coming from?
I've been using Perl since the 4 to 5 migration. Before that, I was
mainly a C/C++ person. Before that, assembler. Perl5 is the best
language I've ever used, but lately it's had some enterprise-level
scalability problems that I need to solve, if I'm going to keep
using it. Hence, I'm helping with Perl6.
When do you think Perl 6 will be released?
Sooner than people think... maybe a robust alpha within six months,
I bet. People are worried about the length of time it's taking to
get through the initial decisions, but most of the hard ones have
already been done. It's going to pick up dramatically after the next
two or three Apocalypses.
Why are you doing this?
Because I've had to work in five different languages over the past
few years, and they all suck, each in their own special way.
Horribly. If I'm going to continue programming as a career, I want
to work in a language that, as much as possible, takes the grunt
work out. I don't like re-solving the same design patterns umpteen
times. That's something a computer should do for me.
Why am I volunteering for documentation? Dunno, seemed like that
effort was falling behind, since everyone keeps asking the same
questions, over and over (like me, for example). And I can type
fast. And I've got lots of experience at herding cats, which can't
hurt...
You have 5 words. Describe yourself.
Programmer, Manager, Writer, Optimist, Cynic.
Do you have anything to declare?
I've grown to hate most technical terms, because nobody uses them to
mean the same way. So I have an allergic reaction to descriptions
that use a lot of big words to explain something that should be Much
More Obvious. You'll find I post a lot of "please clarify" messages,
to try to beat that out of people. :-) It doesn't *always* mean I'm
dense, though sometimes it does. Sometimes it means "No -- really.
Is that your final answer?"
Acknowledgements, requests and the third thing.
This summary was once again brought to you from the comfort and security
of a GNER Express train running between Newark and London, and from the
greater comfort and security of my armchair at home. Production was
abetted by industrial quantities of site tea (in the case of GNER) and
Earl Grey China Moon tea (in the armchair).
Proofreading was mostly done by Piers Cawley, so you can blame him if
there are any outrageous typos.
And, as the postamble usually goes, if you didn't like this summary,
what are you doing still reading it? If you did like it, please consider
one or both 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.
* Send feedback, flames, money and/or a tenchi-masa goban with a set of
thickish yuki grade shell and slate stones in mulberry bowls to
<mailto:pdcawley@;bofh.org.uk>.
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?
