HAProxy protocol version 1.5 support
(see http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt) for
applications using io-streams. The proxy protocol allows information about a
networked peer (like remote address and port) to be propagated through a
forwarding proxy that is configured to speak this protocol.

WWW: http://hackage.haskell.org/package/io-streams-haproxy