default.nix

{ config, pkgs, lib, ... }:

with builtins;
let
  filename = "init.el";
  buildCommand = ''mkdir -p $out; emacs -Q --script "assets/org-build.el" -f make-init-el > $out/init.el'';
  buildEnv = { buildInputs = [pkgs.emacs25-nox]; };
  buildPath = (pkgs.runCommand "init" buildEnv buildCommand).outPath;
in {

  programs.emacs = {
    enable = true;
    package = pkgs.emacsMacport;
    extraPackages = epkgs: [
      epkgs.badger-theme
    ];
  };

  home.file.".emacs.d/init.el".text = readFile "${buildPath}/init.el";

}

tree

.
├── assets
│   ├── org-build.el
│   ├── org-export.el
│   └── style.css
├── default.nix
└── init.org