anchor.diff:  { stdenv, fetchurl
  -, ejabberd ? null, mysql ? null, postgresql ? null, subversion ? null, mongodb ? null
  +, ejabberd ? null, mysql ? null, postgresql ? null, subversion ? null, mongodb ? null, mongodb-tools ? null
   , enableApacheWebApplication ? false
   , enableAxis2WebService ? false
   , enableEjabberdDump ? false
  
positive.code: assert enablePostgreSQLDatabase -> postgresql != null;
  assert enableSubversionRepository -> subversion != null;
  assert enableEjabberdDump -> ejabberd != null;
  assert enableMongoDatabase -> mongodb != null;
  
  stdenv.mkDerivation {
    name = "dysnomia-0.4";
  
negative.code:     ++ stdenv.lib.optional enableMySQLDatabase mysql.out
      ++ stdenv.lib.optional enablePostgreSQLDatabase postgresql
      ++ stdenv.lib.optional enableSubversionRepository subversion
      ++ stdenv.lib.optional enableMongoDatabase mongodb
      ++ stdenv.lib.optional enableMongoDatabase mongodb-tools;
  
    meta = {
      description = "Automated deployment of mutable components and services for Disnix";
  