use warnings;
use strict;
use Data::Dumper;
use Algorithm::Combinatorics qw(combinations);

my @array = qw(A B C D);
for (1 .. 4) {
    my @combos = combinations(\@array, $_);
    print Dumper(\@combos);
}

__END__

$VAR1 = [
          [
            'A'
          ],
          [
            'B'
          ],
          [
            'C'
          ],
          [
            'D'
          ]
        ];
$VAR1 = [
          [
            'A',
            'B'
          ],
          [
            'A',
            'C'
          ],
          [
            'A',
            'D'
          ],
          [
            'B',
            'C'
          ],
          [
            'B',
            'D'
          ],
          [
            'C',
            'D'
          ]
        ];
$VAR1 = [
          [
            'A',
            'B',
            'C'
          ],
          [
            'A',
            'B',
            'D'
          ],
          [
            'A',
            'C',
            'D'
          ],
          [
            'B',
            'C',
            'D'
          ]
        ];
$VAR1 = [
          [
            'A',
            'B',
            'C',
            'D'
          ]
        ];