anchor.diff:  
     meta = {
       homepage = http://librdf.org/;
  -    platforms = stdenv.lib.platforms.linux;
  +    platforms = stdenv.lib.platforms.unix;
     };
   }
  
positive.code: 
    nativeBuildInputs = [ perl pkgconfig ];
  
    buildInputs = [ openssl libxslt curl pcre libxml2 ]
      ++ stdenv.lib.optional withMysql mysql.connector-c
      ++ stdenv.lib.optional withSqlite sqlite
      ++ stdenv.lib.optional withPostgresql postgresql
  
negative.code: { stdenv, fetchurl, pkgconfig, openssl, libxslt, perl
  , curl, pcre, libxml2, librdf_rasqal, gmp
  , mysql, withMysql ? false
  , postgresql, withPostgresql ? false
  , sqlite, withSqlite ? true
  