Re: guix-shell?

[Ludovic Courtès]

David Thompson <address@hidden> skribis:

> Okay, so after digging into nix's source code a bit, I've learned a few
> things.  nix-shell is really just a symlink to nix-build, and it doesn't
> seem to use profiles at all!  When nix-build is called as 'nix-shell',
> it's behavior changes.  From the manual: "The command nix-shell will
> build the dependencies of the specified derivation, but not the
> derivation itself."

Ooh, OK.  Interesting.

> I can see that the nix-build script exits before adding the derivation
> to the store when called as 'nix-shell'.
>
> Here's the relevant Perl source code:

[...]

> (Thank you for choosing Scheme, btw)

Yup.  :-)

> I found it confusing to have the build script also handle the shell via
> some conditional logic.  I think Guix could do it better.

+1

> I will implement 'guix shell' if I can get your opinion on the best
> approach to take.  Would you tweak guix/scripts/build.scm to handle
> the special case or export the necessary procedures and create a
> guix/scripts/shell.scm module?

The problem with a command that spawns a shell IMO is that it does not
compose well: you get a new shell (which shell program is actually
run?), and you can influence a running shell, or use it in a script,
etc.

So instead I would imagine a command like:

  guix environment emacs

which would build the dependencies of Emacs, and then output the search
path as per ‘guix package --search-paths’, so that one can just source
it and be done.

In addition, one could do things like:

  guix environment -l foo.scm

Things like that.

WDYT?

Thanks,
Ludo’.