Re: Improving the speed of guix time-machine for development environments

[Ludovic Courtès]

Richard Sent <richard@freakingpenguin.com> skribis:

>    2. Less maintainence burden to regularly update pinned commits,
>    particularly as a channel dependency tree grows.
>
> I feel that soft-pinning strikes a balance between those two goals that
> is useful when dependencies on a frequently updated channel are unlikely
> to break between commits.
>
> Elaborating on 2.2, consider a dependency chain that looks like
>
>    _______
>   /       \
>  /         v 
> Guix-->A-->B
>
> If B hard-pins Guix to "foo" and A is updated to Guix "bar", B needs to
> update their hard-pinned Guix commit in channels.scm to >= "bar" to have
> a functional development environment again. Alternatively, B could
> hard-pin A, but if A is a channel the developers of B control they
> probably want to always use the latest version.
>
> Now you're in a catch-22 situation of "Do we hard-pin Guix in B and
> manually update it every time A's requirements change, or do we not pin
> Guix at all and deal with regular 5 minute pauses during development?"
>
> As channels become more popular and dependency trees grow, this'll
> become even more annoying. If B is only importing a couple Guix modules
> that are unlikely to incompatibly change, it's basically wasted effort.

I see.  I wonder if another mechanism I suggested could help:

  https://lists.gnu.org/archive/html/guix-devel/2024-01/msg00201.html

Especially if the channels.json is published by a CI system.

Thoughts?

Ludo’.