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Perl 6 and the Parrot Project

  • September 12, 2003
  • By Allison Randal, Dan Sugalski, & Leopold Tötsch
  • Send Email »
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Conceptual integrity in turn dictates that
the design must proceed from one mind,
or from a very small number
of agreeing resonant minds.
–Frederick Brooks Jr.
The Mythical Man Month

Perl 6 is the next major version of Perl. It´s a complete rewrite of the inter-preter, and a significant update of the language itself. The goal of Perl 6 is toadd support for much-needed new features, and still be cleaner, faster, andeasier to use.

The Perl 6 project is vast and complex, but it isn´t complicated. The projectruns on a simple structure with very little management overhead. That´sreally the only way it could run. The project doesn´t have huge cash or timeresources. Its only resource is the people who believe in the project enoughto spend their off–hours—their “relaxation” time—working to see it completed. This chapter is as much about people as it is about Perl.

The Birth of Perl 6

Back on July 18, 2000, the second day of the fourth Perl Conference (TPC4), a small band of Perl geeks gathered to prepare for a meeting of the Perl 5Porters later that day. The topic at hand was the current state of the Perlcommunity. Four months had passed since the 5.6.0 release of Perl, andalthough it introduced some important features, none were revolutionary.

There had been very little forward movement in the previous year. It wasgenerally acknowledged that the Perl 5 codebase had grown difficult tomaintain. At the same time, infighting on the perl5–porters list had grown sointense that some of the best developers decided to leave. It was time for achange, but no one was quite sure what to do. They started conservativelywith plans to change the organization of Perl development.

An hour into the discussion, around the time most people nod off in anymeeting, Jon Orwant (the reserved, universally respected editor of the PerlJournal) stepped quietly into the room and snapped everyone to attentionwith an entirely uncharacteristic and well-planned gesture. Smash! A coffeemug hit the wall. “We are *@$!-ed (Crash!) unless we can come up withsomething that will excite the community (Pow!), because everyone´s getting bored and going off and doing other things!(Bam!)” (At least,that´sbasically how Larry tells it. As is usually the case with events like this, noone remembers exactly what Jon said.)

Awakened by this display,the group started to search for a real solution.The language needed room to grow. It needed the freedom to evaluate newfeatures without the obscuring weight of legacy code. The communityneeded something to believe in, something to get excited about.

Within a few hours the group settled on Perl 6, a complete rewrite of Perl.The plan wasn´t just a language change, just an implementation change,orjust a social change. It was a paradigm shift. Perl 6 would be the community´s rewrite of Perl, and the community´s rewrite of itself.

Would Perl 6, particularly Perl 6 as a complete rewrite, have happened without this meeting? Almost certainly. The signs appeared on the lists, in conferences,and in journals months in advance. If it hadn´t started that day, itwould have happened a week later, or perhaps a few months later, but itwould have happened. It was a step the community needed to take.

In the Beginning...

Let´s pause and consider Perl development up to that fateful meeting. Perl 6is just another link in the chain. The motivations behind it and the direc-tions it will take are partially guided by history.

Perl was first developed in 1987 by Larry Wall while he was working as aprogrammer for Unisys. After creating a configuration and monitoring sys-tem for a network that spanned the two American coasts, he was faced withthe task of assembling usable reports from log files scattered across the network.The available tools simply werent up to the job. A linguist at heart,Larry set out to create his own programming language, which he called perl.He released the first version of Perl on December 18, 1987. He made it freelyavailable on Usenet (this was before the Internet took over the world,remember), and quickly a community of Perl programmers grew.

The early adopters of Perl were system administrators who had hit the wallwith shell scripting, awk,and sed. However, in the mid-1990s Perl´s audience exploded with the advent of the Web, as Perl was tailor-made for CGIscripting and other web–related programming.

Meantime, the Perl language itself kept growing, as Larry and others keptadding new features. Probably the most revolutionary change in Perl (untilPerl 6, of course) was the addition of packages, modules, and object-oriented programming with Perl 5. While this made the transition periodfrom Perl 4 to Perl 5 unusually long, it breathed new life into the languageby providing a modern, modular interface. Before Perl 5, Perl was considered simply a scripting language; after Perl 5, it was considered a full-fledgedprogramming language.

Larry, meanwhile, started taking a back seat to Perl development andallowed others to take responsibility for adding new features and fixing bugsin Perl. The Perl 5 Porters (p5p) mailing list became the central clearing-house for bug reports or proposed changes to the Perl language, with the“pumpkin holder” (also known as the “pumpking”) being the programmer responsible for implementing the patches and distributing them to the restof the list for review. Larry continued to follow Perl development, but like aparent determined not to smother his children, he stayed out of the day–to–day development, limiting his involvement to situations in which he wastruly needed.

Although you might think that the birth of the Perl 6 project would be thefirst nail in the coffin for Perl 5, that´s far from the case. If anything, Perl 5has had a huge resurgence of development, with Perl 5.7.0 released only twoweeks after the initial decision to go ahead with Perl 6. Perl 5.8, spear-headed by Jarkko Hietaniemi and released in July 2002, includes usable Uni-code support, a working threads interface, safe signals, and a significantimprovement of the internals with code cleanup, bug fixes, better documentation,and more than quadrupled test coverage. Hugo van der Sanden is thepumpking for 5.9–5.10. Plans for those releases include enhancements tothe regular expression engine,further internals cleanup and a “use perl6ish”pragma that will integrate many of the features of Perl 6. Perl 5 is active andthriving,and will continue to be so even after the release of Perl 6.0.



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