bug#47911: Package outputs should be described in the UI

[Leo Famulari <leo@famulari.name>]

On Tue, Apr 20, 2021 at 11:54:29PM +0200, Ludovic Courtès wrote:
> Leo Famulari <leo@famulari.name> skribis:
> > They can't find `git send-email`, and the Guix package UI doesn't make
> > this clear enough.
> 
> Just a side note: our ‘git’ package uses outputs in a rather unusual
> way.

That's true. And I don't have any other packages in mind, really.

I first had this idea after roptat was talking about adding ocaml
bindings for z3 [0]. He wrote:

"it builds the bindings in a separate output, instead of a separate
package, because they're part of the same source, and it doesn't look
like it's possible to build them separately
[...]
I'm just not very happy it's part of the same package, because it's less
discoverable vs ocaml-z3"

So, I do think there is room for improvement to this aspect of the UI.

> There are other packages that provide different features in
> different outputs, but the majority of multiple-output packages have the
> “standard” outputs: “doc”, “bin”, “lib”, “debug”.

Right, and it would not be worthwhile to add anything to the UI for
these.

The 'output synopsis' would only be printed in the UI if we actually
defined a synopsis for it. That way, we wouldn't have 16000 lines of
noise like "debug symbols for foo" in `guix package --search=.`

> So maybe we could look at the ‘git’ package (can it be split into
> several packages? would that help?) in addition to the UI, and also make
> sure the UI is optimized for the most frequent cases.

Good question. The Git package is super complicated, so I'm not feeling
very motivated to think about how to rewrite it :)

[0] https://logs.guix.gnu.org/guix/2021-03-11.log#194242
https://issues.guix.gnu.org/46329