use Data::Dumper;
 
#- crossproduct of two array refs
sub X2 {
  my ($a,$b)=@_;
  my @result;
  for my $x (@$a) {
    for my $y (@$b) {
      unless (ref($x) eq "ARRAY"){
        push @result, [$x,$y];
      }else{
        push @result, [(@$x,$y)];
      }      
    }
  }
  return \@result;
}
 
use List::Util qw/reduce/;
 
#- crossproduct of list of array refs
sub X { reduce { X2($a,$b) } @_ }
 
my @array = (
    [ "a", "b", "c", ],
    [ "1", "2", "3", "4", ],
    [ "x", "y", ],
); 
 
print Dumper X(@array);