sbool parallelMap2_debug;

static <A, B> L<B> parallelMap2(ThreadPoolExecutor e defaultThreadPoolExecutor(), Collection<A> l, F1<A, B> f) {
  if (l(l) <= 1)
    ret map(f, l);
  ret parallelMap2(iterator(l), l(l), f);
}

static <A, B> L<B> parallelMap2(ThreadPoolExecutor e defaultThreadPoolExecutor(), Iterator<A> it, final int count, final F1<A, B> f) ctex {
  if (e.getPoolSize() == 1)
    ret map(f, iterable(it));
    
  new LPair<B, Int> out;
  if (parallelMap2_debug)
    print("parallelMap2: " + count + " elements, " + poolSize + " threads");
    
  long time = sysNow();
  try {
    int i = 0;
    for (final A o : iterable(it)) {
      ++i;
      final int _i = i;
      e.execute(r { pcall {
        B x = callF(f, o);
        synchronized(out) {
          out.add(pair(x, _i));
        }
      }});
    }
    /*if (parallelMap2_debug)
      print("parallelMap2: scheduling done after " + (sysNow()-time));*/
    e.shutdown();
    e.awaitTermination(1, TimeUnit.DAYS);
  } finally {
    e.shutdown();
  }
  if (parallelMap2_debug)
    print("parallelMap2: main done after " + (sysNow()-time));
    
  ret firstOfPairs(sortBySecondOfPairs_inPlace(out));
}

static <A, B> L<B> lambdaMapLike parallelMap2(IF1<A, B> f, Cl<A> l) {
  ret parallelMap2(l, if1ToF1(f));
}

Began life as a copy of #1015446