echo_server_by_anyevent.pl

use AnyEvent::Socket;
use AnyEvent::Handle;

my $cv = AE::cv;

tcp_server undef, 8000, sub {
    my $hdl;
    $hdl = AnyEvent::Handle->new(
        fh => shift,
        on_read => sub {
            $hdl->push_write(delete $hdl->{rbuf});
        },
        on_eof => sub {},
    );
};

$cv->recv;