#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my @a = ();
my @b = ( undef );

print "\@a is not Empty\n" if (@a);
print "\@b is not Empty\n" if (@b);
print "\@a is not Empty grep\n" if grep { defined($_) } @a;
print "\@b is not Empty grep\n" if grep { defined($_) } @b;

print Dumper \@a;
print Dumper \@b;