是否有F#等同于Scala的承诺？

发布时间：2020-12-16 09:00:56 所属栏目：安全来源：网络整理

导读：在F#中有类似 Scala’s Promise的东西吗？ While futures are defined as a type of read-only placeholder object created for a result which doesn’t yet exist,a promise can be thought of as a writeable,single-assignment container,which complete

在F#中有类似 Scala’s Promise的东西吗？

While futures are defined as a type of read-only placeholder object
created for a result which doesn’t yet exist,a promise can be thought
of as a writeable,single-assignment container,which completes a
future. That is,a promise can be used to successfully complete a
future with a value (by “completing” the promise) using the success
method. Conversely,a promise can also be used to complete a future
with an exception,by failing the promise,using the failure method.

Async的内容涵盖了部分内容,但如果您的代码在Async环境之外运行,则Promises是一个方便的工具. (例如,您可以执行诸如在UI线程中完成Promise之类的操作 – 即使UI环境对Async一无所知也是如此.)

解决方法

.Net相当于一个承诺是 TaskCompletionSource,所以你可以从F#中使用它们.您可以创建Async< T>来自任务< T>使用 Async.AwaitTask,例如

let tcs = new TaskCompletionSource<int>()
let ta: Async<int> = Async.AwaitTask tcs.Task

//complete completion source using `SetResult``SetException` etc.

（编辑：李大同）

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