Writing Emacs extensions in languages other than Lisp

Question

I'd like to take an existing application (written in OCaml) and create an Emacs "interface" for it (like, for example, the Emacs GDB mode). I would prefer to do this without writing a ton of Lisp code. In MVC terms, I'd like for the View to be Emacs, but for the Model and Controller to remain (primarily) OCaml.

Does anybody know of a way to write Emacs extensions in a language other than Lisp? This could either take the form of bindings to the Emacs extension API in some other language (e.g., making OCaml a first-class Emacs extension language) or an Emacs interaction mode where, for example, the extension has a pipe into which it can write Emacs Lisp expressions and read out result values.

Answer 1

I don't know if this will work for your particular problem, but I have been doing something similar using the shell-command-to-string function:

(shell-command-to-string
    "bash -c \"script-to-exec args\"")

So for example, we have existing scripts written in python which will mangle a file, so the above lets me invoke the script via emacs lisp.

A quick google search found this page describing a system to write extensions in Python, so it seems feasible to do what you want... you will just have to see if anyone has written a similar framework for OCaml.

Answer 2

Mike Stone,

I'd like a richer interface than shell-command-to-string provides. PyMacs is interesting. I'll have to look at how the interface is implemented. I suspect it relies on both sides being dynamic to pass data back and forth.

Answer 3

http://www.emacswiki.org/cgi-bin/emacs-en?CategoryExtensionLanguage is a list of all non-Elisp extension languages you can use.

It does appear to be dynamic language centric.

http://common-lisp.net/project/slime/ is missing from that list, as it is not quite an extension language, but an Elisp-Common Lisp bridge. Its source code would show how to communicate back and forth over sockets.

A similar IDE for Erlang is Distel, at http://fresh.homeunix.net/~luke/distel/ (currently down) and http://code.google.com/p/distel/.

Good luck!

Answer 4

There is no "Extension API". Emacs Lisp is way in there, and it ain't moving.

You can run Emacs commands from your other process. Have a look at Gnuserv.

There are plenty of applications where Emacs is the View for a Model/Controller in a separate process. The Emacs GDB interface is a good example. I'm not sure of a simpler example, maybe sql-postgresql?

Answer 5

Try PyMacs.

Answer 6

Someday you may be able to use JavaScript.