net-yail

https://github.com/Nerdmaster/ruby-irc-yail

Net::YAIL is an IRC library written in pure Ruby. Using simple functions, it is trivial to build a complex, event-driven IRC application, such as a bot or even a full command-line client. All events can have a single callback and any number of before-callback and after-callback filters. Even outgoing events, such as when you join a channel or send a message, can have filters for stats gathering, text filtering, etc.