Since you seemed interested.. here is my permutation generator. It takes a base string (should be empty) as its first argument, then refrences to as many lists as you want as the other arguments and returns a refrence to a list containg all the list-element concatination permutations:

my $foo=permute('',[0..2],[0..2],[0..3],[0..2]);

sub permute{
  my $prefix=shift;
  my @arrays=@_;
  my $c=shift @arrays;
  my @ret=();
  foreach(@$c){
    my $f=$prefix.$_;
    if(scalar(@arrays)==0){
      push @ret,$f;
    }else{
      my $t=permute($f,@arrays);
      push @ret,@$t;
    }
  }
  return \@ret;
}
[download]

I'm not really happy with the implementation of it, but I like it in spirit (of course, I'm a big fan of recursive algorithms to begin with).

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