LinqPad 4 中缺少 Observable 引用？

Question

我在 LinqPad 4 中尝试了以下测试，并收到“Observable not in context”错误。 IEnumerable 分支可以工作，而且奇怪的是，我没有收到 IObservable 本身的错误，只是静态方法 Observable.Range 的错误。

static void Main()
{
 IEnumerableSieve();
 IObservableSieve();
}

private static void IEnumerableSieve()
{
 IEnumerable<int> oddsFrom3 = IntsFrom(3, 2);
 List<int> cache = new List<int>() { 2 };

 IEnumerable<int> primes = oddsFrom3.
  Where(candidate => cache.TakeWhile(prime => prime * prime <= candidate).
   Where(trialDivisor => candidate % trialDivisor == 0).Count() == 0);

 Console.WriteLine("IEnumerable oddsFrom3:");
 foreach (int p in primes.Take(20))
 {
  Console.WriteLine("{0}", p);
  cache.Add(p);
 }
}

private static void IObservableSieve()
{
 const int bigMax = 1 << 30;

 // Generate the candidates as observables, cache the primes in an IEnum list as before.
 // But it's TERRIBLE that the cache is now of a different TYPE than the thing it's caching.
 // The cache is IEnumerable, and the thing it's caching is an IObservable. 

 IObservable<int> oddsFrom3 = Observable.Range(3, bigMax).Where(i => i % 2 == 1);
 List<int> cache = new List<int>() { 2 };

 IObservable<int> primes = oddsFrom3.
  Where(candidate => cache.
   TakeWhile(prime => prime * prime <= candidate).
   Where(trialDivisor => candidate % trialDivisor == 0).Count() == 0);

 Console.WriteLine("IObservable oddsFrom3 ");

 primes.Take(20).Subscribe(p => { Console.WriteLine("{0}", p); cache.Add(p); });
}

static IEnumerable<int> IntsFrom(int i, int increment)
{
 while (true)
 {
  yield return i;
  i += increment;
 }
}

有什么提示吗？

Answer 1

我找到了。 LinqPad 中的 F4 会弹出一个“添加引用”对话框，从那里一切正常。