You may find this helpful if you should find yourself using Erlang on OS X and you’ve installed it using Macports. After a default installation you’ll need to manually configure your .emacs file for erlang-mode and set your $MANPATH variable correctly, here’s how.

If you’ve installed Erlang with Macports then you may have noticed that when you edit .erl files you’re not entering into erlang-mode, nor is it available to enter into. Here’s how I got erlang-mode working on my system.

Macports will install Erlang into /opt/local/lib/erlang by default. The paths to put in your .emacs file provided in the erlang-mode documentation only need to be tweaked a slight bit to function properly. Here’s what I put in mine:

(setq load-path (cons  "/opt/local/lib/erlang/lib/tools-2.6.4/emacs/" load-path))
(setq erlang-root-dir "/opt/local/lib/erlang")
(setq exec-path (cons "/opt/local/bin" exec-path))
(require 'erlang-start)

Note that you may require setting “tools-2.6.4” to something else if Macports has upgraded it’s distribution of Erlang.

Setting up your $MANPATH variable is fairly simple as well. Just put the string “/opt/local/lib/erlang/man” in a file called ‘erlang’ in /etc/manpaths.d/ and make sure it ends with an empty line. Test this by opening a new terminal and running: **echo $MANPATH grep erlang**. If it doesn’t come back empty then you’ve done it right.