• Permute
  • List::Permutor - Process all possible permutations of a list
  • Algorithm::Permute - Handy and fast permutation with object oriented interface
  • Algorithm::FastPermute - Rapid generation of permutations

MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"

I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).

** The third rule of perl club is a statement of fact: pod is sexy.

Those are a helpful start for a search, but he did say combinations, not permutations. The string "foo foo foo" is a valid combination but would not be a valid permutation of qw(hey foo bar).

--
[ e d @ h a l l e y . c c ]

In addition to what PodMaster suggests, you may try a few snippets available here in the Monastery:

• merlyn's Permutations and combinations
• tye's Permuting with duplicates and no memory
• shotgunefx's Non- recursive permutation of arrays.

++ cchampion!
Thanks for the helpful nodes, and everyone, now that I know the word is "permutation", I can super search for it and come up with more nodes. Thanks again!

After some research, I have decided that the word "permutation" is not what I wanted, and halley's comment about my looking for "combinations" is correct.
This node: http://www.perlmonks.org/index.pl?node_id=128286
Does everything I want, thanks again tye!

#!/usr/bin/perl -w

use strict;

use vars qw(@array);
@array = qw( hey foo bar );

combinations(scalar(@array), [], \@array);

sub combinations
{
  my($count,$sofar,$remaining)=@_;
  
  if (!$count)
  {
    print join(" ",@$sofar),"\n";
    return;
  }

  combinations($count-1,[@$sofar],[@$remaining]);
  foreach my $r (@$remaining)
  {
    combinations($count-1,[@$sofar, $r], [@$remaining]);
  }
  
}
[download]

It's a recursive technique that selects all possibilities for each position in the output array, including leaving it empty. Each call to combinations iterates through all possible values for the current position, then calls itself to determine what can go in the subsequent positions.

A possible bug is that it outputs all of ('foo','',''), ('','foo',''), and ('','','foo'), even though all are the single word 'foo'. If that's a problem, you can store the combinations into an array then filter out duplicates.