Nix Recipe: Setup Python

This is a nix recipe for building and running python in a virtual nix environment.

Step 1: Create shell.nix

Create shell.nix with following:

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let
nixpkgs = import (builtins.fetchTarball https://github.com/NixOS/nixpkgs/archive/20.03.tar.gz) {
  overlays = [];
  config = {};
};

in
with nixpkgs;

stdenv.mkDerivation {
  name = "python-env";

  nativeBuildInputs = [
    zsh
    vim
    python37
    python37Packages.pip
    python37Packages.virtualenv
  ];

  # ENV variables
  PROJDIR = "${toString ./.}";

  # Post Shell Hook
  shellHook = ''
    echo "Using ${python37.name}"

    [ ! -d '$PROJDIR/python-dev' ] && virtualenv python-dev && echo "SETUP python-dev: DONE"
    source python-dev/bin/activate
    # python -m pip install -r requirements.txt
  '';
}

Note:

Here, the nix packages are installed from 20.03 release.
virtualenv is installed and activated, and python requirements are installed in this environment (via requirements.txt file).

Step 2: Run nix shell

Now run below command to build and start using python-3.7 in your virtual environment.

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nix-shell --pure shell.nix