Nix shell for python with mutable python modules (I.e. `pip install ...` works like in a virtualenv`)

default.nix

with import <nixpkgs> {};

let
  python = pkgs.python38.buildEnv.override {
    # throw in some default stuff that is always nice to have
    extraLibs = with pkgs.python38Packages; [
      numpy
      ipython
      jupyter
      pandas
    ];
  };
in
pkgs.mkShell {
  buildInputs = with pkgs; with python.pkgs; [
    pip
    setuptools
  ];
  shellHook = ''
    alias pip="PIP_PREFIX='$(pwd)/_build/pip_packages' \pip"
    export PYTHONPATH="$(pwd)/_build/pip_packages/lib/${python.executable}/site-packages:$PYTHONPATH"
    export PATH="$(pwd)/_build/pip_packages/bin:$PATH"
    unset SOURCE_DATE_EPOCH
  '';
}