A random number, observable generator in Rx, without closing over a Random value.

gistfile1.cs

IDisposable generator = Observable.Generate<Tuple<Random, int>, int>(
  new Tuple<Random, int>(new Random(), 0),
  value => value.Item2 < 100,
  value => new Tuple<Random, int>(value.Item1, value.Item2 + 1),
  value => value.Item1.Next(0, 100), scheduler).Subscribe(Console.WriteLine);