IAsyncEnumerable UnFold

UnFold.cs

static async IAsyncEnumerable<T> UnFold<T, TAcc>(Func<TAcc, Task<(bool Next, IAsyncEnumerable<T> Values, TAcc Acc)>> f, TAcc seed)
{
    var acc = seed;
    var result = default((bool Next, IAsyncEnumerable<T> Values, TAcc Acc));
    do
    {
        result = await f(acc);
        await foreach (var value in result.Values)
            yield return value;

        acc = result.Acc;
    } while (result.Next);
}