[eulenteufel]

In this case I think it is important to distinguish nix (the package manager) and nixpkgs (the popular package repository / distribution used with nix).

Packaging python applications with nix is doable, but you have to specify the exact versions of your dependencies and for that you can't easily use nixpkgs.

Nixpkgs tries to keep a minimum number of packages (like Arch or Debian as well), so each of the dependencies will typically only occur with one minor version for each release of nixpkgs.

We could still use the nixpkgs to build our application but we have to override each of our dependencies to the right version, but that approach can get quiet tedious for a large number of dependencies.

Fortunately there are tools to automatically generate your dependencies from a requirements.txt such as mach-nix or pip2nix.