In Nix extra dependencies or modes are usually specified by taking additional arguments such as fullDependencies or interactive.

You can then use this in the .nix file to tell it how it should be built differently if these are set. Users would have to specify an override for these options in their nixpkgs configuration, which isn't ideal but is possible.

Ok, thanks. I'll leave that for later because I'm not sure if all the optional dependencies even exist in nixpkgs yet and it's a bit of work to add the missing ones.

@jluttine while Nikola is indeed used as an application, I could very well imagine that users want to use it in conjunction with libraries that may be available only on certain Python python versions. This is also why pelican e.g. is inside python-packages.nix. Therefore, I recommend using buildPythonPackage and putting it in python-modules and calling it from python-packages.nix.

Regarding the extra dependencies. These are only Python libraries, right? In that case they can just use nix-shell or python.withPackages or python.buildEnv.

Ok, I'll make that fix (application -> module) today perhaps. Anyway, I couldn't get it working with Python 2 because Nix contains only Python 3 supported version of doit, which is a dependency of Nikola. Python 2 support would require older doit 0.29.0 (which on the other hand doesn't support Python 3.3). Is there any sensible way to support Python 2 then?

@jluttine doesn't seem like there is. You can disable it on Python 2.

I now made it a Python module instead of an application.

I also added an upgrade of a dependency ws4py because Nikola needed that in order to work properly. Ping @rickynils, the maintainer of ws4py.

Regarding doit Python 2 support, perhaps that nix definition should be written in such a way that if using Python 2, it would install a different version of itself. Or is that bad practice?

Oh, actually doit is a Python application, not a module..

@jluttine its an applicationt/tool, but in order to use it you need to write Python code, for which you need an environment where all libraries are compatible with eachother. Therefore, at least within Nixpkgs, its location is in python-packages.nix.

It seems that Nikola uses doit as a Python library, that is, it imports lots of stuff from it. So perhaps doit should be moved to Python modules? And then, Python 2 support could perhaps be gained by using different versions of doit for different Python versions within the doit nix definition.

I just rebased my commits on latest upstream/master. Is there something to fix or is this good to merge?