ReactiveFizzBuzz

Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reactive.Linq;

namespace ReactiveFizzBuzz
{
  class Program
  {
    static void Main(string[] args)
    {
      IObservable<string> fizzbuzz = FizzBuzz();
      fizzbuzz.Take(20).Subscribe(Console.WriteLine);
    }

    private static IObservable<string> FizzBuzz()
    {
      return Observable.Generate(
        1,
        _ => true,
        i => i + 1,
        i => i % 15 == 0 ? "FizzBuzz"
          : i % 3 == 0 ? "Fizz"
          : i % 5 == 0 ? "Buzz"
          : i.ToString());
    }
  }
}