Re: ’guix package --export-manifest’ using ’@version’?

[zimoun]

Hi,

On Thu, 07 Jul 2022 at 09:57, Ludovic Courtès <ludo@gnu.org> wrote:

> (Nitpick: it *is* stateless, in the sense that it only depends on Guix
> itself, not on the state of the machine where it is being run.)

I will not argue about what we call state here. :-)


> ‘--export-manifest’ emits a comment (shown above) explaining that the
> manifest is symbolic and that one needs channel info to replicate the
> exact same environment.

I do not understand what you mean by «symbolic» here.


> It is a departure from traditional package managers, and admittedly
> surprising to newcomers.  However, my take on this is that we should be
> very upfront about symbolic vs. exact reproducibility.  We would muddy
> the waters if we gave version strings the same importance as in other
> tools, when we know that a version string means very little.

I miss about what you disagree because «We would muddy the waters if we
gave version strings the same importance as in other tools, when we know
that a version string means very little.» is the exact root of my
comment.

By returning,

        (specifications->manifest
        (list "python" "python-numpy"))

or

        (specifications->manifest
        (list "python@3.8" "python-numpy@1.17"))

depending on the current Guix is just doing that: «muddy the waters».


Instead, I think ’--export-manifest’ should *always* return:

        (specifications->manifest
        (list "python" "python-numpy"))

without ’@x.y.z’.  Other said, be in agreement with the comment:

;;                               This is "symbolic": it only specifies
;; package names.  To reproduce the exact same profile, you also need to
;; capture the channels being used, as returned by "guix describe".

and not sometimes ’package name’ and sometimes ’package name + version’;
as if version string has a special meaning.


To be honest, I do not understand: on one hand, we are advocating that
version string is not enough for reproducibility.  On the other hand, we
output version string with a comment «version string is useless, you
need a channel file for replicating».


Since I am missing a point, could you explain more?


Cheers,
simon