use strict;
use constant NULL => "";

my @a = (1,2,3);
my @b = ();
my @c = ("");
print "a is empty: " . is_null(@a), "\n";
print "b is empty: " . is_null(@b), "\n";
print "c is empty: " . is_null(@c);


sub is_null {
    my @a = @_;
    (@a == NULL) ? "true" : "false";
}