What are some useful or interesting infinite gener

Question

What are some clever uses for infinite generators? I've seen lots of seemingly trivial examples like "list all even numbers", but I assume there must be others that have more applicability to real-world scenarios. Concrete examples (in any language that support generators) appreciated!

I'll give a trivial sample as an answer.

Answer 1

Look at the Haskell code on http://rosettacode.org/wiki/Hamming_numbers#Haskell; that uses lazy lists (which are somewhat like generators) in a creative way to list all Hamming numbers.

Answer 2

Trivial example: yield Fibonacci numbers one at a time (sans overflow checking, in C#):

public static IEnumerable<double> Fibonacci()
{
    double n_minus2 = 1;
    double n_minus1 = 1;
    yield return n_minus2;
    yield return n_minus1;

    while(true)
    {
        double n = n_minus2 + n_minus1;
        yield return n;
        n_minus2 = n_minus1;
        n_minus1 = n;
    }
}

Answer 3

A random generator might be considered clever use.