Undef.pm

package Undef;

sub new { bless \my $a, $_[0] }
sub AUTOLOAD { Undef->new }
use overload
    '""' => sub {""},
    lt   => sub { $_[2] ? $_[1] lt "" : "" lt $_[1] },
    le   => sub { $_[2] ? $_[1] le "" : "" le $_[1] },
    gt   => sub { $_[2] ? $_[1] gt "" : "" gt $_[1] },
    ge   => sub { $_[2] ? $_[1] ge "" : "" ge $_[1] },
    eq   => sub { "" eq $_[1] },
    ne   => sub { "" ne $_[1] },
    bool => sub { 0 == 1 },
    '0+' => sub {undef};

1;