f# - 错误 F# - c# async 调用 : converting Threading. Tasks.Task 到 Async<'a>

Question

当我尝试从我的 F# 代码调用 C# 库中的异步方法时。
我收到以下编译错误。

This expression was expected to have type Async<'a> but here has type Threading.Thread.Tasks.Task

SendMessageAsync在 C# 库中并返回 Threading.Thread.Tasks.Task<MyType>

let sendEmailAsync message = 
    async {
        let! response = client.SendMessageAsync(message)
        return response
    }

Answer 1

用于在 Task<'T> 之间转换和 Async<'T>有一个内置Async.AwaitTask功能。

在普通 Task 之间转换和 Async<unit>您可以创建一个辅助函数:

type Async with
    member this.AwaitPlainTask (task : Task) =
        task.ContinueWith(fun t -> ())
        |> Async.AwaitTask

然后你可以这样称呼它:

let sendEmailAsync message = 
    async {
        let! response = Async.AwaitPlainTask <|client.SendMessageAsync(message)
        return response
    }

当然，在这种情况下，响应不能是 () 以外的任何内容。 ，所以你不妨写一下:

let sendEmailAsync message = Async.AwaitPlainTask <|client.SendMessageAsync(message)