Re: Reproducible environments

[ludo@gnu.org (Ludovic Courtès)]

Konrad Hinsen <konrad.hinsen@fastmail.net> skribis:

> Here's an example (a simplified version of the real situation that motivated
> me to check out Guix):
>
>    - I need to use Program X that depends on libraries A and B.
>    - The current versions are A-1.1 and B-42.0.1.
>    - X requires "1.0 or later" for A but "41.*"  for B, because
>      version 42.* of B is not fully backwards compatible.
>
> If there's no Guix commit that has both A and B in the required
> version range, then the easiest way to get what I need is to use an
> older Guix commit for installing B than I use for A.

That works if you use ‘guix package -i’ to incrementally build the
profile, using different Guix commits; but it prevents you from using
the declarative ‘--manifest’ approach.

> In fact, the only other alternative I see is to add a package definition
> for the old version of B to a later Guix commit. That's likely to be
> much more difficult.

It depends, but not necessarily.  It’s particularly easy to maintain
different versions of leaf packages, as shown in Figure 4 of the paper.

Ludo’.