one line echo server in python.

echo.py

import socket
import itertools
(lambda port, s=socket.socket(socket.AF_INET, socket.SOCK_STREAM):
          s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) == None and 
          s.bind(('', port)) == None and
          s.listen(5) == None and
          list(map(lambda c: 
                   c[0].sendall(c[0].recv(1024)) and
                   c[0].close(),
                   (s.accept() for _ in itertools.count(1)))) != None and
          s.close())(PORT)