I have been working on an erlang bittorrent client for too many years at the moment. The reason it takes so long to get the code up and running is that it is a hobby project and that I have plenty of time doing it right. So at the moment the code works, but it does not have the stability I would like it to have in the long run. But the code does work for downloading smaller things and I would like to have more hackers on the project. To document my setup, I better explain what is used from the perspective of development. The editor is emacs with the distel mode on top of it. See The Distel Googlecode site. The distel program allows me to dynamically upload recompiled code to a running erlang node so I can cut down the fix time to a minimum. For a dynamically typed language this is quite important as most bugs are related to wrong types. Of course I run the standard Erlang distribution, without HiPE. I have not found the reason to compile code for speed yet as the code eats less than 1% CPU power when running. All database table access in the current code is linear, so there are definitely room for improvement and it will be needed as you want to download more than a single torrent file. The code is kept in a GIT repository at repo.or.cz and the bug tracker is on the google code site. I tend to keep the master branch in a stable baseline state so if you want to hack you better base your work on that. Also, I tend to keep my own main working branch in the repository as well so you can track what I am doing which is not yet ready to go into the baseline. Do I like hacking Erlang? Yes and no. I really like the language, but the lack of a static type system is seriously pissing me off at the moment. But you can't have it all and Erlang does have a good production quality system which is rather hard to find with most other esoteric languages. The closest contenders being Haskell and Ocaml.