Infinity() and TakeWhile() as a stream, instead of a while loop.

infinity.cs

void Main()
{
    var records = GetRecordStream();
    foreach (var record in records)
    {
        SaveRecord(record);
    }
}

private IEnumerable<string> GetRecordStream()
{
    return Infinity<int>().Select(x => ReadNextRecord()).TakeWhile(x => x != null);
}

private IEnumerable<T> Infinity<T>()
{
    return new[] { default(T) }.Cycle();
}

public static class Extensions
{
    public static IEnumerable<T> Cycle<T>(this IEnumerable<T> source)
    {
        while (true)
            foreach (var i in source)
                yield return i;
    }
}