anchor.diff:  
   let
     inherit (bootPkgs) ghc;
  -
  -  rev = "3e3a096885c0fcd0703edbeffb4e47f5cbd8f4cc";
   
     # TODO(@Ericson2314) Make unconditional
     targetPrefix = stdenv.lib.optionalString
  
positive.code: 
  in
  stdenv.mkDerivation rec {
    inherit version rev;
    name = "${targetPrefix}ghc-${version}";
  
    src = fetchgit {
      url = "git://git.haskell.org/ghc.git";
      inherit rev;
      sha256 = "06slymbsd7vsfp4hh40v7cxf7nmp0kvlni2wfq7ag5wlqh04slgs";
    };
  
  
negative.code: 
      echo -n "${buildMK}" > mk/build.mk
      echo ${version} >VERSION
      echo ${src.rev} >GIT_COMMIT_ID
      ./boot
      sed -i -e 's|-isysroot /Developer/SDKs/MacOSX10.5.sdk||' configure
    '' + stdenv.lib.optionalString (!stdenv.isDarwin) ''
  