sclass MechListDependentCaches<A> {

  Map<S, MechListDependentCache<A>> byList = ciMap();

  O maker; // func(S) -> A

  transient Lock lock = lock();

  *(O *maker) {}

  A get(S name) {

    MechListDependentCache<A> listCache;

    {

      lock lock;

      listCache = byList.get(name);

      if (listCache == null)

        byList.put(name, listCache

          = MechListDependentCache(name, maker));

    }

    ret listCache!;

  }

}