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== Rakudo *'s Really Really Release Ready

How do you know when a new programming language is ready to be released?
You try porting a real software framework to it. I recently completed a
port of a Perl 5 framework to the Rakudo implementation of Perl 6, and
guess what? It just works! This is my story...

After only a short ten year wait, a Perl 6 implementation is scheduled
for release this month. Rakudo * (aka Rakudo Star) 1.0 will be
inaugurated on July 29th, 2010. Is it ready? That certainly depends on
your expectations, but I am here to make the case that it is a usable
programming language with at least one killer feature that will interest
programming language addicts (like me).

I am an <a href="http://acmeism.org">Acmeist Hacker</a>, which is to say
that I only like to work on projects that serve many programming
languages. I have lots of these projects: <a
href="http://yaml.org">YAML</a>, <a href="http://testml.org">TestML</a>
and <a href="http://jsync.org">JSYNC</a> are three that I have been
actively hacking on recently.

YAML, as you likely know, is a serialization language for all
programming languages. TestML is a unit test language for all
languages. It is useful for porting software (like YAML) and making
sure it passes the exact same tests, everywhere. JSYNC is new. It's an
attempt to combine the simplicity and robustness of JSON with the
completeness of YAML.

A month ago, I gave a talk about Acmeism at <a
href="http://yapc2010.com/yn2010/">YAPC::NA</a>. Afterwards, one of the
attendees, Nick Patch, and I decided to work on a JSYNC port to Perl 6.
Since all the tests for the Perl 5 version of JSYNC are written in
TestML, we decided that we would first need to port the TestML framework
from Perl 5 to Perl 6. A month later, I can happily say that <a href="http://github.com/ingydotnet/testml-
pm6">TestML</a> has been completely (it passes all tests!) ported to
Perl 6/Rakudo. The JSYNC port has not yet been started, but I did manage
to write a fledgling <a href="http://github.com/ingydotnet/yaml-
pm6">Perl 6 YAML module</a> along the way (with all of its tests written
in TestML!!).

What was it like to work in Perl 6? Read on!

TestML is a small to medium sized framework. It consists of a half dozen
object oriented modules. Prior I had written it in <a href="http://github.com/ingydotnet/testml-
pm">Perl 5</a> and in <a href="http://github.com/ingydotnet/testml-
py">Python</a>. The Perl 5 version is over a 1000 lines of code, not
including the tests. Since TestML is a <strong>language</strong>, it
needs to be compiled and executed. This accounts for TestML::Parser
(which is driven by TestML::Parser::Grammar), and TestML::Runner. The
runner class needs a subclass to connect it to an actual existing test
framework; in Perl's case TestML::Runner::TAP. TestML::Document is a
collection of classes that define the compilation unit. Then there is
TestML::Bridge to connect TestML to the application you are testing, and
a standard library called TestML::Standard. All of this code is very
very dynamic, ie introspection based.

TestML itself, started with a <a
href="http://testml.org/specification/language/">TestML
Specification</a> which consists mostly of a grammar written in a
pseudo grammar language. The grammar language is a top down set of
productions and rules all of which eventually terminate into simple
regular expressions (regexps). I turned this grammar into a <a href="http://github.com/ingydotnet/testml-
grammar">YAML data structure</a> and used the same YAML for the Python
and Perl implementations. The implementations also use a <a href="http://github.com/ingydotnet/testml-
tml">common test suite</a>, which is, of course, written in TestML.
The Perl 6/Rakudo port was done, when the implementation passed all
these tests!

When Nick Patch and I started hacking at YAPC, he suggested that we use
<a href="http://perlcabal.org/syn/S05.html">Perl 6 Regexes</a>, the new
parsing technology that Perl 6 uses, instead of my YAML grammar stuff. I
agreed, because I really wanted to learn this. This decision turned out
to be life changing! We actually plopped the old YAML productions into a
new Perl 6 module called TestML::Parser::Grammar, and spent just over an
hour tweaking a few sigils to make it properly compiling Perl 6. But not
only did it compile, it JUST FRICKIN WORKED! We had a passing parse
test. The hard part was over.

Or so I thought. It took me a few weeks (and many a shaved yak) to get
the last test passing. Rakudo is, um..., an adventure. I discovered and
reported about a dozen bugs. I spent countless hours looking into crazy
problems. It was a pretty even split between me learning a new language,
a stupid programming mistake on my part, Rakudo not doing that part of
Perl 6, and Rakudo just sucking it. The one part of Rakudo that never
let me down was its amazing community. People hanging out on #perl6 and
holding my hand as I danced (and danced and danced) barefoot across the
bed of flaming coals that is Rakudo.

Part of the reason it took me so long, is that Rakudo is
sloooooooooooow. No getting around that one for the time being. If your
expection of Rakudo * 1.0 includes blazing speed... fuhgedabowdit! But
if you don't mind taking a coffee break while your code runs far enough
to produce a nice stack trace, give Rakudo a whirl. Luckily, I cut my
hacking teeth writing mainframe code, where I did just that for years.
That's why, I'm sure, I am forever addicted to coffee.

Rakudo has pretty good error reporting. Once in a while. Sometimes you
get a full stack trace with a nice human touch error message (obviously
written by Larry Wall) patting you on the back and saying "well, I know
you tried really hard, and it would have been fine in Perl 5, but now
you need to put a space after that twigil about halfway across line
369...". Many times you just get "Unable to parse blockoid, couldn't
find final '}' at line 141". Oh really? What the heck is a blockoid,
and, um, WHICH FRICKIN FILE??

I could go on and on about the fear and loathing but hey, trying to live
in the future is never easy and I, for one, welcome our new Parrot-based
Overlords. So how about Perl 6 as a <em>language</em>? As an Acmeist, my
goal is to learn new languages and to spread goodness to all of them
equally. My take so far on Perl 6 is that it's better than Perl 5. It
feels really nice to code in. I also learned Python this year, and
contributed a few modules to <a href="http://pypi.python.org/pypi">their
CPAN</a>. I find Python to be even nicer than Perl 6, except for one
important part...

<big>Perl 6 Regexes</big>

<em>Perl 6 Regexes</em> is Perl 6's killer feature. As somebody who has
been searching for good parsing technology for over a decade, I really
appreciate the thought put into this. It makes writing parsers a fairly
simple task. As an Acmeist, I think it is vital that all languages have
this technology. Since it was so easy for me to turn my homebaked TestML
parser grammar into Perl 6 Regexes (P6R), I am already convinced that I
can take a useful subset of P6R and make it work everywhere!

... <strong>*sigh*</strong> yet another project ...

<big>Conclusion</big>

<em><strong>Is Perl 6 Ready?</strong></em> It is ready enough for <strong>Rakudo</strong>!

<em><strong>Is Rakudo Ready?</strong></em> It is ready enough for <strong>TestML</strong>!

<strong>Is TestML Ready?</strong> It is ready enough for an <strong>Acmeist</strong> port of <strong>Perl 6 Regexes</strong>!




-- Tags: perl6 testml rakudo ingy acmeism python perl yaml jsync tap testing unittest json parsing