在F#中创建操作以使用c#方法 [英] Create an action in F# in order to use a c# method

问题描述

我想从HttpListener的Owin实现中使用此方法:

I would like to use this method from Owin implementation of HttpListener :

public static IDisposable Create(AppFunc app, IDictionary<string, object> properties)

AppFunc的签名如下:

AppFunc has a signature like this :

IDictionnary<string,Object> -> Task

我想创建一个任务，但是它需要一个动作，但是我不知道如何在F#中完成它.到目前为止，我管理的最好的方法是使用此问题中的代码:

I wanted to create a task but it requires an action, and I failed to know how to do it in F#. The best I managed so far was using the code in this question :

module CsharpAction

open System

type Wrapper<'T>(f:'T -> unit) =
      member x.Invoke(a:'T) = f a

let makeAction (typ:Type) (f:'T -> unit) = 
    let actionType = typedefof<Action<_>>.MakeGenericType(typ)
    let wrapperType = typedefof<Wrapper<_>>.MakeGenericType(typ)
    let wrapped = Wrapper<_>(f)
    Delegate.CreateDelegate(actionType, wrapped, wrapped.GetType().GetMethod("Invoke"))

program.fs

program.fs

let yymmdd1 (date:DateTime) = date.ToString("yy.MM.dd")
    let printSuccess = fun() -> printfn "Success %s" (yymmdd1 DateTime.Now )
    let actionTask = CsharpAction.makeAction (typeof<string>) (printSuccess)
    let mutable properties = Dictionary(dict [("fooKey", new Object())])


    let server = OwinServerFactory.Create((fun (props) -> new  Task(actionTask)) , properties)

但随后它告诉我:该表达式应具有类型操作，但此处具有类型委托

我应该从F#中执行对C#代码的操作吗?或者我应该在c#代码上工作以便给f#带来一些好处，例如等待委托而不是采取行动?

Should I give from F# an action to c# code? or should I work on the c# code in order to give f# some niceties , for instance waiting for delegate instead of action ?

我正在调侃我的知识极限，我确实感到了痛苦.可以肯定的是，我将学到很多东西，但是如果您愿意帮助我迈出第一步……

I am flirting with the limits of my knowledge and I do feel the pain. Pretty sure, I will have to learn a lot, but if you would be so kind as to help me climb the first steps...

推荐答案

您无需使用反射即可在F#中创建委托.您可以完全放弃代码的第一部分(您的 CsharpAction 模块).

You don't need to use reflection to create delegates in F#. You can ditch the first part of your code altogether (your CsharpAction module).

对于第二段代码，请尝试以下操作:

As for the second chunk of code, try this:

open System
open System.Collections.Generic
open System.Threading.Tasks

let yymmdd1 (date : DateTime) = date.ToString "yy.MM.dd"
let printSuccess () = printfn "Success %s" (yymmdd1 DateTime.Now)

let server =
    let actionTask = Action printSuccess
    let properties = Dictionary (dict ["fooKey", obj ()])
    OwinServerFactory.Create((fun props -> new Task (actionTask)), properties)

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