anchor.diff:      sha256 = "f0551f1af2f008a8a14a888b70c0557e00dd04f9ae309ac91897306cd04a6668";
     };
   
  -  buildInputs = [ghc perl gmp ncurses];
  +  buildInputs = [ghc perl gmp ncurses] ++
  +    (if stdenv.isDarwin then [darwinInstallNameToolUtility] else []);
   
     buildMK = ''
       libraries/integer-gmp_CONFIGURE_OPTS += --configure-option=--with-gmp-libraries="${gmp}/lib"
  
positive.code: 
    preConfigure = ''
      echo "${buildMK}" > mk/build.mk
    '';
  
    configureFlags=[
  
negative.code:       stdenv.lib.maintainers.marcweber
        stdenv.lib.maintainers.andres
      ];
      platforms = stdenv.lib.platforms.linux ++ stdenv.lib.platforms.darwin;
    };
  
  }
  