C# SplitEvery

private static IEnumerable<IEnumerable<T>> SplitEvery<T>(this IEnumerable<T> xs, int n)

{

    return xs.Unfold(ys => ys.Take(n), ys => ys.Any(), ys => ys.Skip(n));

}

private static IEnumerable<T> Unfold<T>(this T x, Func<T, T> h, Func<T, bool> p, Func<T, T> t)

{

    for (var i = x; p(i); i = t(i))

        yield return h(i);

}