in reply to Brute force perl

Ok. A semi-working GA implementation. This fitness function was the best I could think of, and suggestions are very welcome. Also, sorry for not DRYing the code. That's what happens when you get me excited :)

You will, again, want to redirect stderr to /dev/null :). With 50 generations, it took about 17 seconds wall-clock time to run on my machine.

Update: Hmm. One thing I notice is that things like '<text>' or q~<text>~ get generated a lot. I've subtracted points in my fitness function for that sort of ``cheating'', but as I do so, the GA just ``finds'' more ways to ``cheat''. As it is, unless I can think of some more sophisticated fitness function (one that somehow calculates actual usefulness of the code), the current one will just keep growing as I try to (clumsily) parse the perl. (And we all know that goes. It isn't "Nothing but perl and jagh can parse Perl", is it? :)

Update2: Fixed the mess that was the call to $ga->init(). Thank you, jdporter.

Update3: Tweaked the fitness function. I'm also putting the code at my site, to avoid spamming PM with trivial updates as I play. Anything significant will end up back here. 

#!/usr/bin/perl -w
use strict;

sub fitness {
  my ($chars) = @_;
  my $s = join '', @$chars;

  my $f = system('perl', '-ce', $s);
  ## zero and an immediate return if it fails to compile
  if ($f == 0) {
    $ret = 10;
  } else {
    return 0;
  }
  ## quotes and POD is cheating.  Comment char isn't included,
  ##   so don't bother with it.
  $ret-=10 if (substr($s, 0, 1) eq '=');  #subtract if it's a POD
  $ret-=10 if ($s =~ /^q(.).*?(\1)$/);    #q() string?
  $ret-=10 if ($s =~ /^([`'"]).*(\1)$/);  # quoted strings or backtick
+s

  ## Spaces at the start and end are a lesser form of cheating
  $ret-=2 if ($s =~ /^ /);
  $ret-=2 if ($s =~ / $/);

  $ret++ if ($s =~ /\w \w/); # space separated words are kinda cool.

  if ($ret < 0) { $ret = 0 };
  return $ret;
}

use AI::Genetic;
my $ga = new AI::Genetic(
  -fitness    => \&fitness,
  -type       => 'listvector',
);

my @chars = ( 32..34,36..64,91..126 );
$_ = chr($_) for @chars;
$ga->init([ map { [@chars] } 1..20 ]);

$ga->evolve('randomTwoPoint', 50);
my $chars = $ga->getFittest->genes();;
print "Best score = ", $ga->getFittest->score(), ".\n";
my $s = join '',@$chars;
print "$s\n";

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Re: GA perl (was: Brute force perl)
by jdporter (Paladin) on Jun 12, 2007 at 19:50 UTC

    Ech... 

    my @chars = ( 32..34,36..64,91..126 );
$_ = chr($_) for @chars;

$ga->init([ map { [@chars] } 1..20 ]);

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