This is a wrapper around libtelnet, a C library for handling Telnet streams, including option negotiation, &c. As a cleartext protocol, Telnet is thorougly unsuitable for use on the open internet, but you might have a niche where it makes sense:
This library hews closely to the interface provided by the C libtelnet, so reading the excellent C documentation will help you. The short version goes something like this:
Define an event handler of type
Network.Telnet.LibTelnet.EventHandler. This function receives
callbacks that tell you what received data should be propagated to
the application, and what bytes need to be sent out over the
Pass your event handler (and some other flags) to
Network.Telnet.LibTelnet.telnetInit, which will give you access
Telnet, a garbage-collected state tracker.
Tell the state tracker that data has arrived on the socket, or that you want to send data to the socket, by passing it to the library's other functions.