On (11/22/11 11:30), Bernardo Barros wrote: -~> If I still may: -~> -~> roll-back and reproducible configuration was already proposed in the past? -~> -~> The idea raised by Nix devs was the a purely functional approach was a -~> way to implement it. Of course people can have similar ideas with -~> other techniques. -~> -~> If it a very practical question because I'm sure all Arch users in -~> some point or another had to do a roll-back after a complex system -~> update, and then they find themselves in a difficult situation to -~> figure out how to revert all those changes. -~> -~> Pro Audio users, for instance, might want to have their system -~> configuration in a state just before the change that broke lv2 support -~> on Ardour. -~> -~> Nix approach may be not the only one, but their ideas let people see -~> the difference between same packages build with different libs, or -~> know to set a exact system configuration more easily. But config files are always preserved, and severe breakage is avoided by using testing. Where does the roll-back fit in here? Next, it is OK to have /nix/store/<hash>-gcc, but what about /nix/store/<hash>-libpng? Even a minor upgrade requires relinking? IMHO, somebody needed to write a phd thesis, so this problem came up. As a research project NixOS is fine. But as a sustainable distro it's not. Another example that is unlikely to lift off is Qubes OS which is probably the most secure linux distro, but highly unpractical. The question which I always have in such cases is why not bring your ideas to something already mature like dpkg/rpm? Probably they did ask on respective ML and got rejected after being unable to address the above and similar questions. -- Leonid Isaev GnuPG key ID: 164B5A6D Key fingerprint: C0DF 20D0 C075 C3F1 E1BE 775A A7AE F6CB 164B 5A6D