Subject: [bug#39020] Lean won't work with the emacs mode

From: Maxim Cournoyer <[email-masked]>
Date: Tue, 07 Jan 2020 16:39:33 -0500

Hello Arvid,

Arvid Marx <[email-masked]> writes:

> The emacs mode for Lean (which doesn't appear to be packaged yet, but
> of course works via MELPA etc.) expects some sort of root directory for
> Lean, which is not given simply because binaries and other files are
> put into separate directories. This of course makes Lean impossible to
> use as intended. However, I'm not quite sure how this would be fixed in
> practice, as I'm not aware of any suitable directory hierarchy in such
> a case.
>
> Any ideas?

When writing the package definition for the Emacs Lead mode, the code
could be rewritten to refer to the absolute path of the files/programs
it uses from the Lean project, by patching it with `substitute*' uses,
for example.

If that is not easy to do, another idea would be to create some kind of
overlay directory which would flatly collect all the items needed then
refer to that (the items would be symlinked to their real location).
See the `union-build' procedure of the (guix build union) module of
Guix.

HTH!

Maxim