Re: Packages for old Emacs versions

[zimoun <zimon.toutoune@gmail.com>]

Hi Philip,

If I read correctly, the repositority [1] provides many recipes which
create various Emacs VM.  Cool!

Well, from my point of view, these should live in a channel.  Maybe the
channel guix-past is a good location.  Somehow, it would be better to
have a channel with binary substitutes.

That's the easy part, somehow.  Using one of these old Emacs VM, then
the user cannot install any Emacs package via Guix -- because the Emacs
packages provided by Guix are bytecompiled by the emacs-build-system
using the package emacs-minimal and thus although the bytecode is
"stable", there is not guarantee that it is compatible.  Concretely,

    guix install emacs@24 emacs-foo

then 'M-x foo' and who knows if it would work.  The Emacs packages have
to be rebuild using the correct Emacs VM -- in the example Emacs 24.

From my point of view, the best is to use packages transformations.
Give a look at:

    https://issues.guix.gnu.org/41732

for instance, let say 'package-with-explicit-emacs' and it would ease to
get one old Emacs VM and Emacs packages build with it.  WDYT?


This 'package-with-explicit-emacs' could be provided by Guix itself;
which help for testing 'emacs-next', say.

The old Emacs VM could be in a channel, say guix-past.  Then, this very
same transformation could be applied.


Cheers,
simon

1: https://git.sr.ht/~pkal/guix-emacs-historical