C＃中的异步是否与F＃中的异步相同？

Question

C＃4.5中的异步实现与线程使用方式中的F＃2完全相同吗？

Answer 1

They are different. The main difference is that C# uses standard .NET Task<T> to represent asynchronous computations while F# uses its own type called Async<T> .

More specifically, the key differences are:

• AC# async method creates a Task<T> that is immediately started ( hot task model) while F# creates a computation that you have to start explicitly ( generator model). This means that F# computations are easier to compose (you can write higher level abstractions).

• In F# you also get better control over how is the computation started. You can start a computation using Async.Start to start it in the background or Async.StartImmediate to start it on the current thread.

• F# asynchronous workflows support cancellation automatically, so you do not have to pass CancellationToken around.

• Perhaps another consequence of the first point is that F# async workflows also support tail-recursion, so you can write recursive workflows (this would not work easily in C#, but C# does not use this programming style)

I wrote a more detailed article about this topic: Asynchronous C# and F# (II.): How do they differ?