There are probably many ways to do this. Chances are there is some whizzy one-liner using Quantum::Superpositions or some such - but I haven't had time to look.

There are 2ⁿ-1 possibilities (where n is the length of your input array) and that suggested (to me) looking at the binary digits of each number from 1 to 2ⁿ-1. That's what this solution does. It probably isn't the most elegant, and I suspect it is not the most efficient either.

use strict;
use Data::Dumper;

my @firstArray = ( "item1", "item2", "item3" );

my $n = @firstArray;
my @results;

for my $i (1..2**$n-1) {
    my @selection;
    for my $j (0..$n-1) {
        if ($i & 2**$j) {
            push @selection, $firstArray[$j];
        }
    }
    push @results, \@selection;
}

print Dumper(\@results);
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