I am using haskell-mode for Emacs. I succeeded at creating etags for my haskell project on every save by hasktags, however, the cabal dependencies can not be navigated to this way. So I wonder: Is there a way to make this source code navigation work for cabal dependencies, too? (as it is easily possible for java-maven projects for example..)
You can try haskdogs, which provides a thin wrapper around hasktags and executes it for your imported modules as well as your own code. It maintains a repository of module sources in ~/.haskdogs and indexes into that.
I'm using it with vi and have been quite happy with it so far.