anchor.diff:        ];
       sha256 = "039agw5rqvqny92cpkrfn243x2gd4xn13hs3xi6isk55d2vqqr9n";
     };
  -
  -  postPatch = stdenv.lib.optionalString stdenv.isDarwin ''
  -    substituteInPlace configure \
  -      --replace '/usr/bin/libtool' 'ar' \
  -      --replace 'AR="libtool"' 'AR="ar"' \
  -      --replace 'ARFLAGS="-o"' 'ARFLAGS="-r"'
  -  '';
   
     configureFlags = [
       (if static then "--static" else "")
  
positive.code:     license = licenses.zlib;
      platforms = platforms.all;
    };
  } // (if stdenv.isDarwin then {
    postInstall = ''
      # jww (2015-01-06): Sometimes this library install as a .so, even on
      # Darwin; others time it installs as a .dylib.  I haven't yet figured out
      # what causes this difference.
      for file in $out/lib/*.so* $out/lib/*.dylib* ; do
        install_name_tool -id "$file" $file
      done
    '';
  } else {}))
  
negative.code: 
  let version = "1.2.8"; in
  
  stdenv.mkDerivation rec {
    name = "zlib-${version}";
  
    src = fetchurl {
  