my @array1 = (1,2,3,4,5);
my @array2 = (4,5,6,7,8);

my %counts;
my @union          = grep ++$counts{$_} == 1, @array1, @array2;
my @intersection   = grep $counts{$_} == 2, @array1;
my @difference     = grep $counts{$_} == 1, @array1;
my @intersection_c = grep $counts{$_} == 1, @array1, @array2;

print "Union:                      @union\n";
print "Intersection:               @intersection\n";
print "Difference:                 @difference\n";
print "Complement of intersection: @intersection_c\n";