sclass ConcurrentEvaluator {
  new L functions;
  L results = synchroList();
  ExecutorService executorService;
  O onNewResult; // Runnable or voidfunc(int)
  volatile bool cancelled;
  
  void add(O f) { functions.add(f); }
  
  void start() {
    executorService = Executors.newFixedThreadPool(coresToUse());
    while (l(results) < l(functions)) results.add(null);
    for _i over functions: {
      final int i = _i;
      executorService.execute(r {
        results.set(i, pcallF(functions.get(i)));
        onNewResult(i);
      });
    }
  }
  
  void onNewResult(int i) { if (!cancelled) pcallF(onNewResult, i); }
  
  L results() { ret cloneList(results); }
  
  void cancel {
    cancelled = true;
    executorService.shutdownNow();
  }
}