anchor.diff:        patch -Np1 -i ${./fix-gem-nix-versions.patch}
       '';
     };
  -  
  -  ncursesw = { propagatedBuildInputs = [ ncurses ]; };
  -  
  +
     nokogiri = {
       buildFlags =
         [ "--with-xml2-dir=${libxml2} --with-xml2-include=${libxml2}/include/libxml2"
  
positive.code:     find "$1" -type f -name "*.rb" | xargs sed -i "s@/usr/bin/env@$(type -p env)@g"
      find "$1" -type f -name "*.mk" | xargs sed -i "s@/usr/bin/env@$(type -p env)@g"
    '';
    
  in
  
  {
    iconv = { buildInputs = [ libiconvOrEmpty ]; };
  
    libv8 = {
  
negative.code:       ];
    };
  
    pry = { gemFlags = "--no-ri --no-rdoc"; };
  
    rails = { gemFlags = "--no-ri --no-rdoc"; };
  
    rjb = {
      buildInputs = [ jdk ];
      JAVA_HOME = jdk;
    };
  
    rmagick = {
      buildInputs = [ imagemagick pkgconfig ];
  
      NIX_CFLAGS_COMPILE = "-I${imagemagick}/include/ImageMagick-6";
    };
  
    sqlite3 = { propagatedBuildInputs = [ sqlite ]; };
  
    xapian_full = {
      buildInputs = [ gems.rake zlib libuuid ];
      gemFlags = "--no-rdoc --no-ri";
    };
  
    xapian_full_alaveteli = {
      buildInputs = [ zlib libuuid ];
    };
  
    xapian_ruby = {
      buildInputs = [ zlib libuuid ];
    };
  
    xrefresh_server =
  