shell.nix

let
  pkgSource = "https://github.com/NixOS/nixpkgs-channels/archive/nixos-19.09.tar.gz";
  pkgTarball = fetchTarball pkgSource;
  pkgs = import pkgTarball { };
  python372 = let
    py = pkgs.python37.override {
      self = py;
      sourceVersion = {
        major = "3";
        minor = "7";
        patch = "2";
        suffix = "";
      };
      sha256 = "1fzi9d2gibh0wzwidyckzbywsxcsbckgsl05ryxlifxia77fhgyq";
    };
    in py;
  project-python = python372.withPackages (ps: with ps; [ virtualenv ]);
in pkgs.stdenv.mkDerivation {
  name = "project";
  buildInputs = [ project-python pkgs.pipenv pkgs.postgresql pkgs.openssl ];
  shellHook = ''
    export PYTHONPATH=$(pipenv --venv)/lib/python3.7/site-packages/:$PYTHONPATH;
    export SOURCE_DATE_EPOCH=315532800 # 1980 (a hack for pipenv to build with zip, which does not support files before 1980)
  '';
}