C# Lambda Lazy List FizzBuzz :)

Ok, so here is my next example of an implementation of the FizzBuzz problem. I'm going to use a combination of C# 3.0's lambda expressions, lazy lists and extension methods!

First, I create a function returning a lazy list over all numbers starting from 1:

static IEnumerable<int> AllNumbers()
{
    int i = 1;
    while (true) yield return i++;
}

Second, I create a function returning a lazy list of strings, being pText every pCount time. I.e. null, null, Fizz, null, null, Fizz.

static IEnumerable<string> FizzBuzz(int pCount, string pText)
{
    while (true)
    {
        for (int i = 0; i < pCount-1; i++)
        {
            yield return null;
        }
        yield return pText;
    }
}

Now, I need a way of combining the values two lists, so I create an extension method for this. It takes another list and a combinator function:

static IEnumerable<T> Combine<T, TA, TB>(this IEnumerable<TA> pA, IEnumerable<TB> pB, Func<TA, TB, T> pCombineFunc)
{
    var i = pA.GetEnumerator();
    var j = pB.GetEnumerator();
    while(i.MoveNext() && j.MoveNext())
    {
        yield return pCombineFunc(i.Current, j.Current);
    }
}

And here is the whole FizzBuzz program, returning a list of strings being 1, 2, Fizz, 4, Buzz...:

static IEnumerable<string> FizzBuzz()
{
    return AllNumbers().Combine(
        FizzBuzz(3, "Fizz").Combine(FizzBuzz(5, "Buzz"), (x, y) => x + y),
        (x, y) => (y != "") ? y : x.ToString());
}

To write the result to the console, I use this main function:

static void Main(string[] args)
{
    foreach (string fizzBuzz in FizzBuzz().Take(100))
    {
        Console.WriteLine(fizzBuzz);
    }
}

Thats it! Nice and easy eh? :) Hope you liked it and perhaps makes you look into C# 3.0, if you haven't already? You can always download Visual Studio 2008 C# Express for free if you want to try it out!

Edit: Changed generic parameters <T> to html-characters. Changed C# 3.5 to 3.0 (thank u Gustaf :))