static HashMap<Set<S>, Class> loadFunctions_cache = new HashMap;

static Class loadFunctions_cached(S... functions) {
  ret loadFunctions(asList(functions));
}

static Class loadFunctions(L<S> functions) {
  Set<S> functionSet = new TreeSet<S>(functions);
  synchronized(loadFunctions_cache) {
    Class c = loadFunctions_cache.get(functionSet);
    if (c == null)
      loadFunctions_cache.put(functionSet, c = loadFunctions(functionSet));
    ret c;
  }
}