Posted by Tom Moertel
Fri, 26 Oct 2007 17:23:00 GMT
Alex Smith, a 20-year-old EE student in the UK, proved that the 2, 3 Turing machine is universal. In doing so, he was able to claim the $25,000 prize that Stephen Wolfram offered for the first proof (or disproof) of the 2, 3 machine’s universality.
This story has been getting a lot of attention lately, but one part of
the story has not: that the Perl programming language is featured in the proof. In his documentation of the proof, Universality of Wolfram’s 2, 3 Turing
Machine,
Smith wrote, “I have written several Perl programs, to demonstrate the
constructions given in the proof and to interpret the systems given in
various conjectures.” Smith’s proof includes no fewer than 7 Perl
programs.
Go Perl!
Posted in perl
Tags math, perl, proof
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Posted by Tom Moertel
Tue, 25 Sep 2007 23:04:00 GMT
I am on the planning committee for the Pittsburgh Perl
Workshop. So far, it’s been an interesting
ride. Last year was the first PPW, and it went surprisingly well. In
the post-conference surveys, 94 percent of respondents said they
wanted to come back for another PPW, so we committed ourselves to
repeating the grueling conference-planning process for
2007. (Fact: making big commitments like this is much more likely
to happen if you’re drinking beer at the time.)
Now a year has gone by, and PPW 2007 is
only three weeks away. This year’s conference is 100% larger – two
full days – and offers a new, much-asked-for option: a
one-day introductory course
to give programmers new to Perl a quick dose of the language so they
can dive into the rest of the conference. This year’s conference also
offers a full-length Hackathon for those who feel the urge to code
at the conference.
The main attraction, however, is the conference’s wide array of
technical talks. We have retained
the same mix of industry and academic speakers that attendees said
they liked so much last year. Indeed, our speaker list includes some
of last year’s most fascinating speakers, as well as many new speakers
drawn from the world of Perl. No matter what your interests are,
you’ll find talks for you at PPW 2007. (I’m particularly interested
in the talks on continuation-based web applications, the cool new
stuff in Perl 5.10, and the Moose object system.)
All of this is to say: Do not miss PPW 2007! Where
else are you going to find so many interesting people, so many
fascinating talks, and so many opportunities to have fun and make
friends while learning useful stuff, all for so little expense?
(Regular admission is only $70, and students get a big discount.)
Get your ticket now because
over half of the seats are already gone.
I hope to see you there.
Posted in perl
Tags conferences, perl, pittsburgh, ppw, ppw2007
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Posted by Tom Moertel
Mon, 20 Aug 2007 23:18:00 GMT
This year’s Pittsburgh Perl Workshop is shaping up
to be uber-techno-awesome. This year, it’s two big days of
lively technical talks and full-force Perl festiveness. Yes, come
October, programmers of all stripes will gather in Pittsburgh over the
weekend of the 13th to grab a slice of the fun. A big slice. And you – yes
you, my friend – should be there.
Lots of interesting talks are flowing in, but it’s not too late
to grab a speaking slot. If you have
anything interesting to say about Perl, now is your time. 20-
and 50-minute slots are available. To claim one, just go to
pghpw.org and submit a talk
proposal. It’s easy. But
act now, before it’s too late!
If you have any interest in Perl, you’ll want to be at PPW
2007, and if you have anything to say about
Perl, you’ll definitely want to speak at PPW
2007.
Don’t miss your opportunity. Seize the day!
Posted in perl
Tags perl, pghpw, ppw2007, speaking
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Posted by Tom Moertel
Thu, 21 Jun 2007 18:38:00 GMT
Last week I gave a talk on the R statistics
system and Perl for the Pittsburgh Perl
Mongers. The example that threaded through the
talk was something I have written about here before, extracting
useful information from the Internet Movie
Database.
If you’ve read my earlier blog
post
or have used the Grand Unified IMDB Movie Rating Decoder
Ring,
you might find the slides from the talk interesting. They provide
some more details about the R and Perl code used to analyze the IMDB data
and create the decoder ring.
You can get the slides here:
Posted in talks
Tags imdb, perl, R, statistics, talks
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Posted by Tom Moertel
Tue, 12 Sep 2006 21:30:00 GMT
I am on the planning committee for the 2006 Pittsburgh Perl
Workshop and serve as the primary point of contact for
speakers. That means I get the inside scoop on the talks.
And from what I have seen, all I can say is, These
talks kick ass. Well, actually I can say one more thing:
If there is any possible way you can manage to get yourself to Pittsburgh, Pennsylvania
on Saturday, 23 September 2006, do not wait, do not mull
it over, register now for the Pittsburgh Perl Workshop.
If you miss this one, you’ll probably end up weeping in front of your keyboard for a long, long time.
PPW ’06 has speakers from the worlds of finance,
bioinformatics, engineering, politics, health care, insurance, Web-2.0
start-ups, environmental monitoring, and mathematics. And they all
have fascinating things to share with you about how they make Perl
work for them and about how you can make Perl work for you.
Registration is only $20 – can you imagine that, in an age when
programming conferences routinely cost hundreds if not thousands of dollars? – and all of the talks show you how to use
Perl to do real work, solve real problems, and make your real life as a
programming professional a whole lot saner. Even if you think
you don’t care about Perl, you ought to be a part of
PPW ’06 just for the rare opportunity to discover something
you may have overlooked. (At $20, when are you ever going to get
a chance like this again?)
Posted in perl, pittsburgh
Tags cool, perl, pittsburgh, ppw, ppw06, stuff, talks
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Posted by Tom Moertel
Thu, 17 Aug 2006 06:21:00 GMT
As promised, here’s a Perl version of a dynamic-programming-based solver
for the Google Code Jam “countPaths” problem. It is a straight
translation of my improved Ruby implementation.
As you might expect, the Perl version was pretty fast. It proved faster than the
other scripting-language implementations I tried (in this rather unscientific benchmark, not to be taken seriously):
All timings were taken while solving the maximum-size, all-the-same-letter
problem on my 1.8-GHz Opteron box.
Here’s the Perl implementation:
#!/usr/bin/perl
# Tom Moertel <tom@moertel.com>
# 2006-08-16
#
# Perl-based solution to the Google Code Jam problem "countPaths".
# See http://www.cs.uic.edu/~hnagaraj/articles/code-jam/ for more.
use strict;
use warnings;
use List::Util 'sum';
use Math::BigInt;
sub count_paths {
my ($grid, $word) = @_;
my $rword = reverse $word;
my $rowmax = $#$grid;
my $colmax = length($grid->[0]);
my ($slab, $sum);
for my $i (0 .. length($rword) - 1) {
my $char = substr $rword, $i, 1;
($slab, my $previous_slab) = ([], $slab);
for my $r (0 .. $rowmax) {
my ($row, $line) = ($grid->[$r], $slab->[$r] ||= []);
for my $c (0 .. $colmax) {
$line->[$c] = $char ne substr($row,$c,1) ? 0 : $i == 0 ? 1 : do {
$sum = 0;
my $clo = $c > 0 ? $c - 1 : $c;
my $chi = $c < $colmax ? $c + 1 : $c;
for my $nr (($r>0 ? $r-1 : $r) .. ($r<$rowmax ? $r+1 : $r)) {
for my $nc ($clo .. $chi) {
$sum += $previous_slab->[$nr][$nc]
if $nr != $r || $nc != $c;
}
}
$sum;
}
}
}
}
sum map @$_, @$slab;
}
print count_paths([("A"x50)x50], "A"x50), $/;
# 3.03835410591851e+47
Update: I simplified the code a whisper by
removing an unnecessary variable
$counts. Here’s a diff
if you’re curious about what’s changed:
--- countpaths.pl.orig 2006-08-18 00:16:56.000000000 -0400
+++ /countpaths.pl 2006-08-18 00:19:30.000000000 -0400
@@ -19,11 +19,11 @@
my $rword = reverse $word;
my $rowmax = $#$grid;
my $colmax = length($grid->[0]);
- my ($counts, $slab, $sum);
+ my ($slab, $sum);
for my $i (0 .. length($rword) - 1) {
my $char = substr $rword, $i, 1;
- ($slab, my $previous_slab) = ($counts->[$i] ||= [], $slab);
+ ($slab, my $previous_slab) = ([], $slab);
for my $r (0 .. $rowmax) {
my ($row, $line) = ($grid->[$r], $slab->[$r] ||= []);
for my $c (0 .. $colmax) {
Update 2: Augmented the introductory paragraph with a parenthetical
comment that reminds readers that these single-fuzzy-data-point-style
timings should not be taken seriously. Also removed the word
“bested,” which might suggest that there is an optimization
contest in play. Please, no wagering.
Update 3: Stripped another variable ($j), which was
completely unused and leftover from previous implementation. (See
why you shouldn’t code late at night?)
Posted in programming, perl, fun stuff
Tags code, countpaths, google, jam, perl, puzzles, wordpaths
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Posted by Tom Moertel
Tue, 27 Jun 2006 18:21:00 GMT
I have a bunch of LectroTest news. LectroTest, as you may know, is a specification-based,
automatic testing system for Perl. It may look like Haskell’s QuickCheck, but it tastes like sweet, sweet Perl.
LectroTest 0.3500 was released
This version adds automatic tools for recording and playing back
failures. Using them, you can automatically build regression-testing
suites and incorporate them into your testing plan. All it takes
is one new line of code:
use Test::LectroTest
regressions => "regressions.txt"; # <-- that's it!
See the docs on CPAN for more.
My thanks to Steffen Müller, who suggested the feature and is already
using it in cool stuff such as Number::WithError.
Slides from “Testing Tips with LectroTest” are now online
You can get the slides from my talk to the Pittsburgh Perl Mongers on
2006-06-14 here: Talk / Testing Tips with
LectroTest.
In the talk, I covered some of the newer LectroTest features, such as
regression testing and Test::LectroTest::Compat, which lets you mix
LectroTest with other Perl testing modules.
The LectroTest Emporium opens!
I have very little artistic ability. Nevertheless, alarming numbers
of people seem to love the fiercely metallic mascot I created for
LectroTest.
At the last Perl Mongers meeting, for example, people
actually told me (somewhat sternly) I should put the adorable LectroTest Robot on
t-shirts. I am now delighted to announce that I have taken their
advice:
Introducing: The LectroTest Emporium
Some important points:
- Yes, it’s a CafePress store
- I’m not making any money on these things
- I’m using direct printing, not heat-transfer printing, so
the Robot won’t crack, feel stiff, or suffer from a yellowish
transfer background. (CafePress has a comparison of the methods if you want the full details.)
Some items I have moral reservations about offering:
- LectroTest Robot Teddy Bear -
Who would be so reckless as to allow something as fierce and as powerful
as the LectroTest Robot to come into direct contact with a defenseless, cuddly
teddy bear?
- LectroTest Robot Baby Bib -
Actually, this is a great idea: your infant and the Robot
exist in a symbiotic relationship. When your baby gets food all over the
bib, the Robot will consume it (using a electrochemical process not
entirely dissimilar to our human concept of “digestion”). Thus is the
baby cleaned and the Robot fueled. It’s win-win.
- LectroTest Robot Dog T-Shirt -
I am fairly certain that the immense weight of the Robot would easily
crush any smaller animal. This product strikes me as a very bad idea.
The T-shirts, on the other hand, are the robot’s meow. Check out the
full collection at The LectroTest Emporium.
Posted in perl, fun stuff, testing, marketing, talks
Tags lectrotest, perl, testing
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Posted by Tom Moertel
Tue, 14 Mar 2006 22:39:00 GMT
Last week I gave a brief talk for the Pittsburgh Perl
Mongers about embedding domain-specific languages
into Perl. The slides from the talk are now available:
Embedding an XHTML template language into Perl.
Posted in programming languages, perl, talks
Tags dsls, perl, pghpm, talks
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Posted by Tom Moertel
Wed, 01 Mar 2006 20:17:00 GMT
The human mind subconsciously corrects mistakes while we read. This mental feature has a nasty drawback for writers: when proofreading, we often miss our own mistakes.
One of the most common writing mistakes that our brains stealthily correct is the the duplicate word problem. For example, the duplicate the words in the previous sentence. Did you catch them?
If so, don’t be too proud of your accomplishment. It is easier to see errors in others’ writing than in your own. Your brain is attuned to your natural writing patterns and much more likely to repair your mistakes without your knowing.
To overcome this problem, some writers recommend reading your work backward, but I think computers are a more practical solution.
Here’s the Perl script that I use to spot duplicate words:
#!/usr/bin/perl -n00
# dupwords.pl - find duplicate words in the input stream
print "$ARGV: para $.: ($1)\n"
while /(\b(\w+)\b\s+\b\2\b)/sg;
I use this script from Emacs via shell-command-on-region. I also use it from the command line to find duplicate-word errors in batch:
find . -name '*.txt' | xargs dupwords.pl
The duplicate-words problem is a favorite for programming cookbooks, so if you don’t like my recipe (or Perl), you have many other options.
Posted in perl, writing
Tags perl, tools, writing
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Posted by Tom Moertel
Tue, 01 Nov 2005 19:41:00 GMT
Over the weekend I attended Damian
Conway’s talk on Sufficiently Advanced
Technologies,
hosted by the Pittsburgh Perl Mongers and
presented at CMU.
Read more...
Posted in programming, perl
Tags conway, damian, perl, talks
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