idg10

[MemoryDiagnoser]
public class SwitchWithBlockingSources
{
    public readonly static IAsyncEnumerable<IAsyncEnumerable<int>> source = AsyncEnumerable
        .Range(0, 1000)
        .SelectAwait(async i =>
        {
            await Task.Yield();
            return AsyncEnumerable
                .Range(0, 1000)

idg10

[MemoryDiagnoser]
public class SwitchWithNonBlockingSources
{
    public readonly static IAsyncEnumerable<IAsyncEnumerable<int>> source = AsyncEnumerable
        .Range(0, 1000)
        .Select(i => AsyncEnumerable.Range(0, 1000));

    [Benchmark]
    public async ValueTask<int> IterativeSingleLogicalThread()
    {

idg10

namespace AsyncEnumerableSwitchSpike;

internal static class SwitchExtension
{
    public static async IAsyncEnumerable<T> Switch<T>(this IAsyncEnumerable<IAsyncEnumerable<T>> sequences)
    {
        IAsyncEnumerator<IAsyncEnumerable<T>>? currentOuterEnumerator = sequences.GetAsyncEnumerator();
        IAsyncEnumerator<T>? currentInnerEnumerator = null;

        try

idg10

// Written as a reply to https://twitter.com/buhakmeh/status/1577738711013335040
// (C) 2022 I D Griffiths

// EnumerableEx from System.Interactive
IEnumerable<BigInteger> FibonnaciEndless() => EnumerableEx.Generate(
    (i: new BigInteger(0), n: new BigInteger(1)),
    _ => true,
    s => (s.n, s.i + s.n),
    s => s.i);

idg10

// Written as a reply to https://twitter.com/buhakmeh/status/1577738711013335040
// (C) 2022 I D Griffiths

IEnumerable<BigInteger> FibonnaciEndless()
{
    BigInteger i = 0, n = 1;
    while (true)
    {
        yield return i;
        (i, n) = (n, i + n);

idg10

public class Person
{
    // This gets rid of the CS8618 warning, but it is
    // A BAD IDEA!
    public string FavouriteColour { get; set; } = "";
}

idg10

var o = (JObject)JToken.Parse(text);
bool hasItem = o.ContainsKey("item");

idg10

if (JToken.Parse(text) is JObject o)
{
    bool hasItem = o.ContainsKey("item");
    Console.WriteLine(hasItem);
}

idg10

var o = JToken.Parse(text) as JObject;
if (o != null)
{
    Console.WriteLine("item is " + (o.ContainsKey("item") ? "present" : "absent"));
}

bool hasItem = o != null ? o.ContainsKey("item") : false;

bool? itemPresence = o?.ContainsKey("item");

idg10

var o = JToken.Parse(text) as JObject;
bool hasItem = o.ContainsKey("item");