The Perl 6 Summary for the week ending 2004-07-04
Another week, another Perl 6 Summary. This is becoming a habit.
Let's do perl6-internals first shall we?
Japhy's Perl 6 rules parser
Last week Jeff 'japhy' Pinyan announced that he'd be working on a Perl 6
rules parser once he'd finished his Perl 5 regex parser. This week saw a
deal of discussion on how his parser worked. The answer seemed to be "It
works the Right Way." Which is good. With any luck Steve Fink will be
able to get this parser and the current (sketchy) Perl 6 compiler
playing well together.
http://xrl.us/ccie
Complexities
Last week Leo had pointed out that we'd need support for complex numbers
in order to get the Piethon stuff running properly. This week there was
some discussion of what was actually needed.
Later in the week Ion Alexandru Morega posted a patch implementing them.
I think Leo spoke for us all when he said "Whee, great, thanks -
applied."
http://xrl.us/ccif
New mailing lists
There was some discussion of how perl6-internals should be broken up. It
looks like we'll see new lists called parrot-internals, parrot-compilers
and parrot-library (for internals hackers, compiler implementers and
library builders respectively). The original perl6-internals will carry
on, but will be focused on the actual internals of Perl 6.
Some, or all, of these lists will be covered in these summaries for as
long as I can keep up.
Stack language for Parrot
In as impressive a delurk as I've seen in a while, Michael Pelletier
announced that he'd been lurking for a while, playing with Parrot and
had implemented a little stack language not entirely unrelated to Forth
which he'd christened "Parakeet". He posted his implementation and got
promptly Warnocked.
http://xrl.us/ccig
GMP and licensing issues
Scott Bronson announced that he'd taken a look at GMP's license and he
didn't think it was incompatible with Parrot's licenses. Dan wasn't
convinced. Scott's still trying to convince him though.
Robert Spier attempted to resolve the problem by pointing everyone at
another possibly suitable library called IMath.
http://xrl.us/ccih
Meanwhile, in perl6-language
Argh! Strings!
Discussion of the various ways of slicing and dicing strings in Perl 6
continued. The issue is that, especially in a Unicode world, there are
many ways of looking at a string, all of which are useful in different
contexts. However, because you can look at a string as a sequence of
bytes, codepoints, graphemes or whatever, then functions like "substr"
get a little weird. If you were to say
$substring = $a_string, 5
then what does the '5' mean?
And that's just one example of where conceptual problems can arise.
I confess that, whenever Unicode comes up, my gut reaction is to keep my
head down and trust that Larry's going to get it right. Certainly the
current formulation seems decently sane; things only get problematic if
you're trying to do something well out of the ordinary.
http://xrl.us/ccii
"if", "loop", and lexical scope
Discussion of Perl 6's new scoping rules (things are generally more
consistent than they are in Perl 5; if a variable is declared inside a
block, or in that block's signature in the case of "-> $a, $b {...}"
type blocks, then that block is its scope) continued. Some people like
the new rules, others don't.
http://xrl.us/ccij
Different OO models
Jonadab the Unsightly One had wondered about having objects inheriting
behaviour from objects rather than classes in Perl 6. The gist of the
answers he received was that it wouldn't be in the core of the language,
but neither should it be too hard to implement something that worked how
he wants.
Undo?
Michele Dondi wondered if Perl 6 would have a built in "undo" function
for rolling back the history of a scalar (say). Rafael Garcia-Suarez
pointed out that the concept wasn't a simple as it first appeared,
especially in the context of threads, closures, side effects. He
suggested that a better approach would be to implement a suitable
transaction/rollback library that handled such things in an application
appropriate fashion rather than using a 'half-baked kludge built into
the base language'. Mark Biggar pointed out that the language already
had hypothetical values, which did pretty much the right thing.
Elsewhere in the thread, Luke Palmer attempted to explain continuations
again. A sandwich was involved.
http://xrl.us/ccik
http://xrl.us/ccim -- Luke makes a continuation sandwich
If not "," then what
Alexey Trofimenko triggered your Summarizer's sense of deja vu when he
asked what was happening to the C-style comma (we're keeping it, more or
less) and proposing a "then" keyword for use in the contexts where Perl
6's new "," didn't quite work the same way as in Perl 5. Which is pretty
much the same as the proposal Luke Palmer made some months ago and which
Larry rejected.
Jonathan Lang pointed out how you'd implement "then" if you needed it
though.
The thread got slightly silly after this (sideways semicolons! I ask
you!). I'm not sure what chromatic was driving at when he suggested a
"meh" operator though.
http://xrl.us/ccin
"map", "grep" and laziness
That man Alexey also had some questions about lazy evaluation. Luke
Palmer attempted to allay his fears by saying that Perl 6 would be
essentially lazy unless you told it otherwise.
http://xrl.us/ccio
Announcements, Apologies, Acknowledgements
Woohoo! Another weekly summary.
If you find these summaries useful or enjoyable, please consider
contributing to the Perl Foundation to help support the development of
Perl. You might also like to send me feedback at
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http://donate.perl-foundation.org/ -- The Perl Foundation
http://dev.perl.org/perl6/ -- Perl 6 Development site
