[bug#54375] Mutable guix shell environments

[Charles]

Thanks for taking a look Liliana. I'm glad you like guix shell detecting a 
local profile.

> $ $SHELL
> $ GUIX_PROFILE=/path/to/profile
> $ source $GUIX_PROFILE/etc/profile

This is basically what I was going for. I just find this useful to be built in. 
When I think "guix shell", I think: "make an environment where I have 
everything I need". If I want to adjust what I need, why do I need to restart 
everything from scratch. If I did not know about guix shell and did all my 
development using ~/.guix-profile, this functionallity would already be 
available.

> Guix is functional by design and we should
not compromise on that.

I totally agree, and I do not think this does compromise it. With my patch, 
guix shells using guix.scm or manifest, would be unchanged. Currently, guix 
shell --profile, has strickly less functionallity than using the profile 
otherwise, this could be confusing (as it is to me). Profiles are not really 
mutable since they use generations; the subject line is a bit of a misnomer.

> As far as using $GUIX_PROFILE tog...

Yeah, before my patch, guix shell --profile, would not be set to the profile 
I'm using. This actually makes sense, because, we are not really using it. Guix 
shell just happens to be using all the same packages that were available in 
that profile. Confusingly, If the profile, is updated, the shell is now out of 
sync with it. My patch should make using guix shell --profile more intuitive.


------- Original Message -------

On Sunday, March 13th, 2022 at 2:51 PM, Liliana Marie Prikler 
<liliana.prikler@gmail.com> wrote:

> Am Sonntag, dem 13.03.2022 um 18:21 +0000 schrieb Charles:
>
> > Subject: [PATCH 2/2] guix: shell: Implicitly use a .guix-profile as -
> >
> > -profile option.
> >
> > * guix/scripts/shell.scm (auto-detect-manifest): Add ".guix-profile"
> >
> > to matches as --profile option
>
> This one LGTM and it even avoids some problems we're having with
>
> caches. I'll keep it open for bikeshedding suggestions w.r.t. the name
>
> of the directory to detect, though.
>
> > Subject: [PATCH 1/2] guix: environment: Enable mutable environments.
> >
> > * guix/scripts/environment.scm (launch-environment launch-
> >
> > environment/fork
> >
> > launch-environment/container guix-environment*): Add #:set-profile?
> >
> > parameter set GUIX_PROFILE
> >
> > when --profile option is used.
> >
> > * guix/scripts/environment.scm (guix-environment*): Profile could
> >
> > point to a
> >
> > profile directory instead of a store directory.
>
> This one not so much. You already have GUIX_ENVIRONMENT set, which
>
> should be enough for lookup purposes. If it's about manipulating PATH
>
> and other environment variables, I think it'd better to do this
>
> manually – you could even spawn a lightweight shell on your own by
>
> simply doing the following:
>
> $ $SHELL
>
> $ GUIX_PROFILE=/path/to/profile
>
> $ source $GUIX_PROFILE/etc/profile
>
> If you want mutable environments, that's the easiest and imho best way
>
> of achieving such a thing. Guix is functional by design and we should
>
> not compromise on that.
>
> As far as using $GUIX_PROFILE together with `guix shell' is concerned, if 
> anything is even holding it back, it's that we don't respect GUIX_PROFILE in 
> the Scheme code that adds those variables. Which to be fair might be for the 
> best, as GUIX_PROFILE is not guaranteed to correspond to this invocation of` 
> guix shell' when people are careless.
>
> That's not to say that support for this couldn't be added, but at the
>
> very least we'd have to be more careful about it.
>
> Cheers