Perl 6 and the Parrot Project

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 to add support for much-needed new features, and still be cleaner, faster, and easier to use.

The Perl 6 project is vast and complex, but it isn´t complicated. The project runs on a simple structure with very little management overhead. That´s really the only way it could run. The project doesn´t have huge cash or time resources. Its only resource is the people who believe in the project enough to 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 (TPC 4), a small band of Perl geeks gathered to prepare for a meeting of the Perl 5 Porters later that day. The topic at hand was the current state of the Perl community. Four months had passed since the 5.6.0 release of Perl, and although it introduced some important features, none were revolutionary.

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

An hour into the discussion, around the time most people nod off in any meeting, Jon Orwant (the reserved, universally respected editor of the Perl Journal) stepped quietly into the room and snapped everyone to attention with an entirely uncharacteristic and well-planned gesture. Smash! A coffee mug hit the wall. “We are *@$!-ed (Crash!) unless we can come up with something that will excite the community (Pow!), because everyone´s getting bored and going off and doing other things!(Bam!)” (At least,that´s basically how Larry tells it. As is usually the case with events like this, no one 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 new features without the obscuring weight of legacy code. The community needed 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,or just 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, it would have happened a week later, or perhaps a few months later, but it would 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 6 is 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 a programmer for Unisys. After creating a configuration and monitoring sys- tem for a network that spanned the two American coasts, he was faced with the 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 freely available 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 wall with 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 CGI scripting and other web–related programming.

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

Larry, meanwhile, started taking a back seat to Perl development and allowed others to take responsibility for adding new features and fixing bugs in 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 rest of the list for review. Larry continued to follow Perl development, but like a parent determined not to smother his children, he stayed out of the day–to– day development, limiting his involvement to situations in which he was truly needed.

Although you might think that the birth of the Perl 6 project would be the first nail in the coffin for Perl 5, that´s far from the case. If anything, Perl 5 has had a huge resurgence of development, with Perl 5.7.0 released only two weeks 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 significant improvement of the internals with code cleanup, bug fixes, better documentation, and more than quadrupled test coverage. Hugo van der Sanden is the pumpking for 5.9–5.10. Plans for those releases include enhancements to the 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 and thriving,and will continue to be so even after the release of Perl 6.0.