I am playing around with an idea like this for editing Clojure in Emacs with cider-mode. You have to manually build the 'thread' that such a code unravel-er would return, but then you can read and edit functions from many files in one buffer. You start with the highest-level function you are interested in, and then pull the definitions of functions it calls into view as needed.

https://github.com/fazzone/multifiles.el/tree/cider-hacks