To provide a bit more context, most of SLIME is just Common Lisp code (https://github.com/slime/slime https://github.com/slime/slime), with a bunch of Emacs Lis

To provide a bit more context, most of SLIME is just Common Lisp code (https://github.com/slime/slime https://github.com/slime/slime), with a bunch of Emacs Lisp code alongside to support interfacing with Emacs. But you don't need that Emacs Lisp code to take advantage of almost all of the functionality SLIME provides. For instance, if you want to know who-calls a function, there's some command in emacs to do it, but all that command is doing is just a bit of elisp code which sends a message to Swank (a server running inside Common Lisp) and Swank invokes some native CL code to figure that out and return the results, then finally a bit of elisp code presents the results in some way. Vim can do the same thing just fine with vimscript/python (what the Slimv plugin uses) or otherwise, the bulk of the work in figuring out the list of callers of some function is done by the CL code (and CL implementation itself).