Data: a1, b2, c3

Cardinality: 1
Permutations:
{a1, b2},
{a1, c3},
{b2, c3},

Data: a1, b2, c3, d4
Cardinality: 2
Permutations:
{{a1, b2}, {c3, d4}}
{{a1, c3}, {b2, d4}}
{{a1, d4}, {c3, d4}}

##</code><code>##

my @data;

if ($cardinality == 1) {

  for (my $i = 0; $i < scalar(@$permlist); $i++) {

    for (my $j = 0; $j < scalar(@$permlist); $j++) {

      push @data, {
        first  => [$$permlist[$i]],
        second => [$$permlist[$j]],
        };
      }
    }
  }

if ($cardinality == 2) {

  for (my $i = 0; $i < scalar(@$permlist); $i++) {

    for (my $j = 0; $j < scalar(@$permlist); $j++) {
				
      for (my $k = 0; $k < scalar(@$permlist); $k++) {

        for (my $p = 0; $p < scalar(@$permlist); $p++) {

          push @data, {
            first   => [$$permlist[$i], $$permlist[$j]],
            second  => [$$permlist[$k], $$permlist[$p]],
            };
          }
        }
      }
    }
  }