Re: Perl 5 compatibility (Re: Larry's Apocalypse 1)
On Thu, 5 Apr 2001, John Porter wrote: Nathan Wiger wrote: the more compatible with Perl5 Perl6 is, the more likely it is to be accepted. I don't believe that's necessarily true. If Perl6 proves to be a significantly better Perl than Perl5, people will adopt it, especially if they're inclined toward the Perl philosophy anyway. (And at first, those are the only people we have to convince.) To this end, sacrificing the Virgin of Perlish Power to the God of Backward Compatibility would be unwise in the extreme. You are correct, but being backwards compatible is unlikely to _cost_ us adherents and might well gain us some. *shrug* Dave
Re: Perl 5 compatibility (Re: Larry's Apocalypse 1)
Dave Storrs wrote: being backwards compatible is unlikely to _cost_ us adherents and might well gain us some. Yes, all other things being equal. But will they be? IOW: at what cost backwards compatibility? -- John Porter
Perl 5 compatibility (Re: Larry's Apocalypse 1)
Ted Ashton wrote: Thus it was written in the epistle of Michael G Schwern, I think [Nate]'s saying that its annoying to have to write any tag that says "Hey, I'm starting a new Perl 6 program here!" at the top of every single program, much in the same way its tiresome to write "int main(...)" in every C program. Then again, we already have to do the #! thing. Not only is it tiresome, it really gets in the way of writing perl6 one-liners. Right, exactly. Perhaps it could be 1) If the code uses "module" or 2) If the executable called ends in 6. Yep, something like this would be cool. But as Dan suggested we'll probably have to let Larry clarify his intent here. I read it as "it would be cool to assume that we're getting real Perl 5 code", rather than as just assuming Perl 5 non-strict policies, but actual Perl 6 code. I agree with Ed that, if you think about it, parsing Perl 5 in the Perl 6 detachable-lexer-parser model shouldn't (hopefully) be any harder than parsing Python (or Parrot :) syntax. Assuming this, then in one way Perl5 compatibility could be a "no-brainer". But the real question is how to distinguish Perl 5 vs 6 reliably. We could have "module main", but like Schwern, my left eye starts twitching and I get hot flashes with "int main" hallucinations. Anyways, it's probably something worth pondering, as the more compatible with Perl5 Perl6 is, the more likely it is to be accepted. The more I've been thinking about the p52p6 translator, the more it bothers me. I just think of the different Fortran versions and that whole mess. -Nate
Re: Perl 5 compatibility (Re: Larry's Apocalypse 1)
Nathan Wiger wrote: the more compatible with Perl5 Perl6 is, the more likely it is to be accepted. I don't believe that's necessarily true. If Perl6 proves to be a significantly better Perl than Perl5, people will adopt it, especially if they're inclined toward the Perl philosophy anyway. (And at first, those are the only people we have to convince.) To this end, sacrificing the Virgin of Perlish Power to the God of Backward Compatibility would be unwise in the extreme. Put simply, I'd take Conway's Perl6 Power Extension Pack over the ability to run my existing programs (which work just fine under my (still functioning) perl5, thanks) under perl6 any day. Put abstractly, if I perceive Perl6 as a new-and-improved, yet vaguely incompatible, upgrade to Perl5, I am much less inclined to adopt it that if I perceive it as a bold stride above and away from Perl5. -- John Porter
Re: Perl 5 compatibility (Re: Larry's Apocalypse 1)
At 02:43 PM 4/5/2001 -0700, Nathan Wiger wrote: Yep, something like this would be cool. But as Dan suggested we'll probably have to let Larry clarify his intent here. Somewhere or other Larry talked about this. Might've been in LA1, might've been somewhere else. I read it as "it would be cool to assume that we're getting real Perl 5 code", rather than as just assuming Perl 5 non-strict policies, but actual Perl 6 code. I agree with Ed that, if you think about it, parsing Perl 5 in the Perl 6 detachable-lexer-parser model shouldn't (hopefully) be any harder than parsing Python (or Parrot :) syntax. To be honest, if we lop out some of the nastier bits of perl 5 that have been contemplated, then making perl 6 grok code that uses them will be reasonably non-trivial. Besides, I really do *not* want to have perl 6 fully compatible with all perl 5 source for another reason. If we say we're not, but some perl 5 code does parse and run, then we get nice brownie points. If, on the other hand, we say we *are* perl 5 compatible, every single silly little incompatibility will be a black mark. Perl 5 is enough of a moving, poorly defined, target that I'd rather not shoot directly at it. Which isn't to say I'd be against a parser plug-in on CPAN that ate perl 5 code--that'd be rather cool. I just don't want to promise that perl 6 will eat all perl 5 code. Dan --"it's like this"--- Dan Sugalski even samurai [EMAIL PROTECTED] have teddy bears and even teddy bears get drunk
Re: Perl 5 compatibility (Re: Larry's Apocalypse 1)
OK, there's probably somthing simple I'm missing here, but... 1. Cuse 5 or Cuse 6 (and, in general, Cuse vervect) import the definitions of the language as it existed at that time (more or less), or die if they can't. (Or run through p52p6, or whatever.) Advantage: matches existing precedent. The real perl 5 won't choke on it, and will even give the right error. 2. If the name of the executable (from argv[0] or the beginning of #!) contains "perl.?[56]", then there is an implicit Cuse 5 or Cuse 6. (And why not any other version number? Just don't ship them in core, please!) Advantage: reasonably non-intrusive. 3. Otherwise, assume perl 6. Advantage: we require trivial changes in existing scripts instead of baggage we'll be carrying around forever. If you object to that much change as an admin, feel free -- install perl6 under the name "perl6", symlink perl5 to it, and make a symlink from perl to perl5. (This would work only if we had #2 follow symlinks until it saw a "perl5" or "perl6", which is probably fine). If you don't have symlinks on your system, then get a better system, use a site-policy file, or bite the bullet and change the #! lines. -=- James Mastros -- The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. He to whom this emotion is a stranger, who can no longer pause to wonder and stand wrapt in awe, is as good as dead. -=- Albert Einstein AIM: theorbtwo homepage: http://www.rtweb.net/theorb/
