[Nix-dev] Nix expressions and latest packages

[Nicolas Pierron]

Hi,

On Mon, Mar 30, 2015 at 1:06 AM, 胡雨軒 <pde-bois at isep.fr> wrote:
> The documentation says Nix conceptually builds package from source but
> relies on stores (some package caches) to download already built packages.

Indeed, the way this works is that we hash the recipe (including its
dependencies) and this hash is used to look-up pre-build packages made
by trusted remotes.

> So there is some set of fixed package versions and system update depends on
> the store update pace, doesn't it?

This mostly depend which channel you are following, we have a stable &
unstable channels which are updated by a buildfarm.  Then by trusting
the buildfarm, you can download anything which is built by it.
On the other hand, you can go extremelly bleeding-edge by pulling the
latest recipes from the github repository of nixpkgs.

> Is it possible to set nix to always download latest versions of installed
> packages,

If you use a channel, then you will mostly be downloading the latest
versions, except if this is not built by the buildfarm (no
redistributable, no maintainer, not supported architecture).

> built it aside the old version and upgrade the system
> automatically?

With a cron job, or similar, yes.

> I know one could think some latest package may be not compatible with each
> other, but this leads me to the next question. I'm planning to use nix
> package manager within Arch Linux distro, so the distro team would do what's
> necessary to avoid incompatibilities.

Nix install its packages in /nix/store, which it assumes to be the
only one to manage.
So we have no conflict with other package managers because we are
using a different set of directories.

> Then, is it possible to configure nix
> to retrieve data both from Arch repositories and from the AUR?

I do not know Arch enough to answer this question precisely.
I know somebody did something similar for debian packages, by mocking
an FHS layout for one program.

-- 
Nicolas Pierron
http://www.linkedin.com/in/nicolasbpierron - http://nbp.name/