anchor.diff:          url = https://projects.archlinux.org/svntogit/community.git/plain/trunk/boost160.patch?h=packages/mongodb;
           name = "boost160.patch";
           sha256 = "0bvsf3499zj55pzamwjmsssr6x63w434944w76273fr5rxwzcmh8";
  -      })
  -      # probably not needed for > 3.4.10
  -      (fetchpatch {
  -        url = https://github.com/mongodb/mongo/commit/218a7b1d4ea3d3b.diff;
  -        name = "pcre-8.41.patch";
  -        sha256 = "1dra51gw130bq78l2yfkdaj0jkha95ikpv4ig21rapbl63ip3znj";
         })
       ];
   
  
positive.code: 
  with stdenv.lib;
  
  let version = "3.4.2";
      system-libraries = [
        "pcre"
        #"asio" -- XXX use package?
  
negative.code: 
    src = fetchurl {
      url = "https://fastdl.mongodb.org/src/mongodb-src-r${version}.tar.gz";
      sha256 = "1wz2mhl9z0b1bdkg6m8v8mvw9k60mdv5ybq554xn3yjj9z500f24";
    };
  
    nativeBuildInputs = [ scons ];
  