CODEWITHSUNDEEP
kotlinasync-awaitkotlin-coroutines
Aaron B
Aaron B

Reputation: 1041

What is the Kotlin equivalent to C# 8's async enumerable?

C# 8 now has IAsyncEnumerable. Is there a Kotlin equivalent to this? For instance, in C# you can await foreach(...) now (with IAsyncEnumerable):

async Task Main()
{
    await foreach(var dt in new Seconds().Take(10))
    {
        Console.WriteLine(dt);
    }
}

public class Seconds : IAsyncEnumerable<DateTime>
{
    public class FooEnumerator : IAsyncEnumerator<DateTime>
    {
        public DateTime Current { get; set; }
        public async ValueTask DisposeAsync() {}
        public async ValueTask<bool> MoveNextAsync()
        {
            await Task.Delay(1000);
            Current = DateTime.Now;
            return true;
        }
    }

    public IAsyncEnumerator<DateTime> GetAsyncEnumerator(CancellationToken cancellationToken = default)
        => new FooEnumerator(); 
}

Upvotes: 3

Views: 759

Answers (1)

hotkey
hotkey

Reputation: 147911

Take a look at the Asynchronous Flow, which seems to be the closest equivalent.

A similar example would be:

fun main() = runBlocking {
    seconds().take(10).collect {
        println(it)
    }
}

fun seconds() = flow<Instant> {
    while (true) {
        delay(1000L)
        emit(Instant.now())
    }
}

I'm using kotlinx-coroutines-core version 1.3.9

Upvotes: 5

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