Implementing a C # Method Returning Task <T> to F #

Question

I am creating a type in F # that inherits from a C # class that provides a method that returns Task<T>in C #. I am trying to decide what would be the best way to do this in F #

Say my C # looks like this:

public class Foo {
    public TextWriter Out { get { return Console.Out; } }

    public virtual Task<SomeEnum> DoStuff() {
        return Task.FromResult(SomeEnum.Foo);
    } 
}

public enum SomeEnum {
    Foo,
    Bar
}

My first pass of inheritance of this type in F # looks like this:

type Bar() =
    inherits Foo()

    override this.DoStuff() =
        this.Out.WriteLineAsync("hey from F#") |> ignore

        System.Threading.Task.FromResult(SomeEnum.Bar)

But a) it does not feel actually asynchronous, and b) it just does not feel - F #.

So, how could I inherit a class Fooand implement a method DoStuffthat expects to return Task<T>?

Answer 1

You can use Async.StartAsTask :

type Bar() =
    inherit Foo()
    override this.DoStuff() =
        async { return SomeEnum.Bar } |> Async.StartAsTask

Async.StartAsTask Async<T> a Task<T>.

Answer 2

aync F # . , Task s. , :

override this.DoStuff() =
    async {
        do! this.Out.WriteLineAsync("hey from F#") |> Async.AwaitVoidTask
        return SomeEnum.Bar
    } |> Async.StartAsTask

Answer 3

I believe that FSharp's way to transfer tasks is to use

var a = Async.AwaitIAsyncResult(somecsharpreturningtask) |> ignore