gistfile1.pl

sub combo {
  my $hash = shift;
  my %hashcopy = %$hash;
  my $list = shift || [];
  my $s = shift || {};
  my @k = (keys %hashcopy);
  if(scalar(@k) == 0) { push @$list, $s; return; }
  my $arr = $hashcopy{@k[0]};
  delete $hashcopy{@k[0]};
  for my $v (@$arr) {
    my %copy = %$s;
    $copy{@k[0]} = $v;
    combo(\%hashcopy, $list, \%copy);
  }
  return $list;
}