Hello Guix!

Idea of adding following features to Guix.

1) Dedicated "guix system -u" separated from "guix system reconfigure". So the difference between "guix system reconfigure" and "guix system -u" would be; the former does changes to system configuration (including adding/upgrading system packages) whereas the latter just upgrades system packages without making changes to system configuration.

2) "guix system --list-packages" lists all system packages in current system generation. Could also add additional parameter (like "guix system --list-packages #sys-gen") to list system packages in a different available system generation.

Regards,
RG.