Bryan O'Sullivan is an Irish hacker and writer who likes distributed systems, open source software, and programming languages. He was a member of the initial design team for the Jini network service architecture (subsequently open sourced as Apache River). He has made significant contributions to, and written a book about, the popular Mercurial revision control system. He lives in San Francisco with his wife and sons. Whenever he can, he runs off to climb rocks.John Goerzen is an American hacker and author. He has written a number of real-world Haskell libraries and applications, including the HDBC database interface, the ConfigFile configuration file interface, a podcast downloader, and various other libraries relating to networks, parsing, logging, and POSIX code. John has been a developer for the Debian GNU/Linux operating system project for over 10 years and maintains numerous Haskell libraries and code for Debian. He also served as President of Software in the Public Interest, Inc., the legal parent organization of Debian. John lives in rural Kansas with his wife and son, where he enjoys photography and geocaching.Donald Stewart is an Australian hacker, currently completing his computer science doctorate at the University of New South Wales, Sydney. Don has been involved in a diverse range of Haskell projects, including practical libraries such as Data.ByteString and Data.Binary, as well applying the Haskell philosophy to real world applications, including compilers, linkers, text editors, network servers and systems software. His recent work has focused on optimising Haskell for high-performance scenarios, using techniques from term rewriting. He is the current editor of the Haskell Weekly News.