let
  pkgs = import ../../../../.. { };

  emacsEnv = pkgs.emacs.pkgs.withPackages (
    epkgs:
    let

      promise = epkgs.melpaBuild {
        pname = "promise";
        version = "0-unstable-2019-06-07";

        src = pkgs.fetchFromGitHub {
          owner = "bendlas";
          repo = "emacs-promise";
          rev = "4da97087c5babbd8429b5ce62a8323b9b03c6022";
          hash = "sha256-XsvPsA/lUzPWyJAdJg9XtD/vLDtk7guG7p+8ZOQ8Nno=";
        };

        packageRequires = [ epkgs.async ];
      };

      semaphore = epkgs.melpaBuild {
        pname = "semaphore";
        version = "0-unstable-2019-06-07";

        src = pkgs.fetchFromGitHub {
          owner = "webnf";
          repo = "semaphore.el";
          rev = "93802cb093073bc6a6ccd797328dafffcef248e0";
          hash = "sha256-o6B5oaGGxwQOCoTIXrQre4veT6Mwqw7I2LqMesT17iY=";
        };

        packageRequires = [ promise ];
      };

    in
    [
      promise
      semaphore
    ]
  );

in
pkgs.mkShell {
  packages = [
    pkgs.git
    pkgs.bash
    pkgs.nix-prefetch-git
    pkgs.nix-prefetch-hg
    emacsEnv
  ];
}