Re: Finding versions of packages

["Ludovic Courtès" <ludo@gnu.org>]

Hi,

zimoun <zimon.toutoune@gmail.com> skribis:

> On Mon, 14 Dec 2020 at 11:38, Ludovic Courtès <ludo@gnu.org> wrote:
>
>> However, it might give the false idea that users can pick
>> package versions independently (as in: I want esbuild X, GCC Y, and Go
>> Z), which is not really the case: packages are interrelated.
>
> Someone tried that on help-guix.  The idea was to recreate a Python
> environment.  It was an extensive use of inferiors: one inferior per
> package.  We already discussed that when discussing how to recreate a
> profile from a <profile>/manifest file.  
>
> Just to point the manual about inferiors:
>
>    Sometimes you might need to mix packages from the revision of Guix
> you’re currently running with packages available in a different revision
> of Guix.  Guix “inferiors” allow you to achieve that by composing
> different Guix revisions in arbitrary ways.
>
> Therefore, I want esbuild X (compiled with GCC A and foo A), GCC Y (compiled with
> foo B) and Go Z (compiled with foo C).  It is technically possible, right?

It is possible, and it’s nice to have.

However, doing such composition on a per-package basis and as the
default way of composing packages is inefficient and, more importantly,
the resulting compositions may not work.  A package written for Python 2
may not work with Python 3, and so on.

Ludo’.