Perl5 - Perl 6 Translations Design Document
Hello all, I'm the student picking up on the translation work lwall started. Since the perl 5 parser is more or less complete, I've headed straight to the translation work. I'm going to be taking on the translations a few at a time, starting with the easiest translations and moving to the more complex. I've got a design document detailing the first few translations I'll be handling, and I'd greatly appreciate feedback and advice. Larry already took a good crack at it, catching a few things I had stupidly thought were simpler then they are, and now it's ready for general review. The current version can be found at http://infohost.nmt.edu/~slatorra/conversionstageone.txt Any advice/comments/criticism on the document and even ideas on implementation would be greatly appreciated. Sage
Re: Perl5 - Perl 6 Translations Design Document
Sage La Torra schreef:
http://infohost.nmt.edu/~slatorra/conversionstageone.txt
Any advice/comments/criticism on the document and even ideas on
implementation would be greatly appreciated.
I think that
split('\s+') - split(/\s+/)
should be
split('\s+') - .split(/\s+/)
--
Groet, Ruud
Re: Perl5 - Perl 6 Translations Design Document
Sage La Torra [EMAIL PROTECTED] wrote:
I've got a design document detailing the first few translations I'll be
handling, and I'd greatly appreciate feedback and advice.
I may be off base here, or in the alternate pointing out a corner case
that's of little significance, but:
-Compound statements: if($foo eq a or $foo eq b or $foo eq c) {...} -
if $foo eq a|b|c {...}
Is there an issue if $foo is tied here, in that (unless the a or b condition
match) $foo will be evaluated three times; for testing against a junction is
it feasible that the compiler can say aha, I'll only evaluate $foo once and
test it three times? Reading $foo may have some real world visible effects
and the semantics would change. The P6 spec may nail this down, but I
haven't time to go look (and I'll surely not have time before I forgot this
thought completely...)
That's all I can pick out from the quick glance I have time for. Have fun!
:-)
Jonathan
Re: Perl5 - Perl 6 Translations Design Document
On Tue, Jun 06, 2006 at 02:06:05AM +0100, Jonathan Worthington wrote:
: Sage La Torra [EMAIL PROTECTED] wrote:
: I've got a design document detailing the first few translations I'll be
: handling, and I'd greatly appreciate feedback and advice.
:
: I may be off base here, or in the alternate pointing out a corner case
: that's of little significance, but:
:
: -Compound statements: if($foo eq a or $foo eq b or $foo eq c) {...}
: - if $foo eq a|b|c {...}
:
: Is there an issue if $foo is tied here, in that (unless the a or b
: condition match) $foo will be evaluated three times; for testing against a
: junction is it feasible that the compiler can say aha, I'll only evaluate
: $foo once and test it three times? Reading $foo may have some real world
: visible effects and the semantics would change. The P6 spec may nail this
: down, but I haven't time to go look (and I'll surely not have time before I
: forgot this thought completely...)
Yes, but I think the translator can assume that most scalar variables
aren't tied, especially if there isn't a tie anywhere else in the file.
Could have a user option to pessimize that, and it should probably be logged
as one of the places the translator guessed. But unlimited tying is
one of the problems with Perl 5 that Perl 6 is trying to control, so it's
sort of natural that the translator would run into this here and there.
Another minor difference is that or guarantees an ordered
short-circuit while | may short-circuit in any order the compiler
pleases. Again, unlikely to be a problem for the variable in the
absence of ties, but if some of the value calculations that can blow
up are guarded by or conditions, then you've got a problem.
We'll definitely need to provide some knobs for the user to turn to
control how much refactoring is attempted.
Larry
Re: Perl5 - Perl 6 Translations Design Document
Sage La Torra wrote: Hello all, I'm the student picking up on the translation work lwall started. Since the perl 5 parser is more or less complete, I've headed straight to the translation work. I'm going to be taking on the translations a few at a time, starting with the easiest translations and moving to the more complex. I've got a design document detailing the first few translations I'll be handling, and I'd greatly appreciate feedback and advice. Larry already took a good crack at it, catching a few things I had stupidly thought were simpler then they are, and now it's ready for general review. The current version can be found at http://infohost.nmt.edu/~slatorra/conversionstageone.txt Any advice/comments/criticism on the document and even ideas on implementation would be greatly appreciated. Looks like a reasonable starting point. I assume that the AST will include comment nodes etc? Sam.
