using System;
using System.IO;
using System.Reactive.Disposables;
using System.Reactive.Linq;

namespace ConsoleApplication8
{
    internal class Program
    {
        private static IObservable<string> GetFiles(string folder, string filePattern)
        {
            return Observable.Create<string>(
                o =>
                {
                    var files = Directory.GetFiles(folder, filePattern);

                    foreach (var file in files)
                    {
                        o.OnNext(file);
                    }

                    var folders = Directory.GetDirectories(folder);

                    foreach (var f in folders)
                    {
                        var x = GetFiles(f, filePattern);
                        x.Subscribe(p => { o.OnNext(p); });
                    }

                    o.OnCompleted();

                    return Disposable.Empty;
                });
        }

        private static void Main(string[] args)
        {
            var o = GetFiles(@"d:temp", "*.*");

            o.Subscribe(p => { Console.WriteLine(p); });

            Console.Read();
        }
    }
}