Hi!

On the one hand, I can only echo Ryan's experience, and I suppose the
experience of most of us: emacs-guix has been a bit broken for a while
now.

I believe it suffers from 2 main issues:

- Geiser is a strong dependency: everything depends from a well-working
  Geiser REPL.

  - Geiser 0.12 broke the REPL setup :(
  - Geiser chokes on large outputs, which happens on any Guix build.  So
    you can't build anything with emacs-guix.

- Emacs-Guix uses private parts of Guix if I'm not mistaken.  Since
  these parts are prone to change, it breaks Emacs-Guix once in a while.

Finally, it seems that Emacs-Guix is mostly unmaintained now:

https://github.com/alezost/guix.el/issues/38#issuecomment-617718043

On the other hand, leveraging the actual Guix API is a saner approach
than parsing the output.

It's what I did in Nyxt:

https://github.com/atlas-engineer/nyxt/blob/2-pre-release-4/libraries/ospama/ospama-guix.lisp

It's fast, reliable, flexible, structured.

> On the other hand, I am interested in building out a formal API for
> tools to interface with Guix without having to depend on its internals
> or parse the output of its CLI commands. This could be a Guile API,
> although I picture json would be a better choice to support diverse
> tooling.

Guix already has a stable API that can be leveraged by any programming
language thanks to the `guix repl` command.  This is what I'm doing in
Nyxt.

> For one example of what I'd want the API for, in my `guix-packaging-
> insert-input` command I need to get the list of available Guix packages,
> and then for the selected package I need to find its scheme symbol. The
> emacs-guix approach to those things is to reach into Guix internal data
> structures and read out that data, which doesn't deliver results in
> practice.

Maybe emacs-guix does not do it well, but `fold-packages` works well for
Nyxt in practice!

> I opt instead to parse the output of the CLI command `guix
> package -A ""` as a tsv, which works as long as Guix doesn't change its
> output, but that's not guaranteed either.

Indeed, I don't think this is the right approach :p

Let me know what you think!

Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/