anchor.diff:    ] ++ optionals stdenv.isDarwin [
       "NATIVE=osx"
       "CLANG=1"
  +  ] ++ optionals (! debug) [
  +    "RELEASE=1"
     ];
   
     postInstall = with stdenv.lib; optionalString (tiles && !stdenv.isDarwin) ''
  
positive.code: { fetchFromGitHub, stdenv, pkgconfig, ncurses, lua, SDL2, SDL2_image, SDL2_ttf,
  SDL2_mixer, freetype, gettext, CoreFoundation, Cocoa,
  tiles ? true }:
  
  stdenv.mkDerivation rec {
    version = "2018-07-15";
  
negative.code:   # src/weather_data.cpp:203:1: fatal error: opening dependency file obj/tiles/weather_data.d: No such file or directory
    # make: *** [Makefile:687: obj/tiles/weather_data.o] Error 1
    enableParallelBuilding = false;
  
    dontStrip = debug;
  
    meta = with stdenv.lib; {
      description = "A free, post apocalyptic, zombie infested rogue-like";
  