anchor.diff:      '';
     };
   
  +  unf_ext = attrs: {
  +    buildInputs = lib.optional stdenv.isDarwin darwin.libobjc;
  +  };
  +
     xapian-ruby = attrs: {
       # use the system xapian
       buildInputs = [ xapian pkgconfig zlib ];
  
positive.code: { lib, fetchurl, writeScript, ruby, libxml2, libxslt, python, stdenv, which
  , libiconv, postgresql, v8_3_16_14, clang, sqlite, zlib, imagemagick
  , pkgconfig , ncurses, xapian, gpgme, utillinux, fetchpatch, tzdata, icu, libffi
  , cmake, libssh2, openssl, mysql
  }:
  
  let
  
negative.code:       "--with-exslt-lib=${libxslt}/lib"
        "--with-exslt-include=${libxslt}/include"
      ] ++ lib.optional stdenv.isDarwin "--with-iconv-dir=${libiconv}";
      buildInputs = lib.optional stdenv.isDarwin darwin.libobjc;
    };
  
    pg = attrs: {
  