F#异步HTTP请求-解析JSON响应

我正在尝试使用以下代码片段 F# 向Firebase发送异步POST请求:尤其是以下操作,它允许匿名登录:

https://firebase.google.com/docs/reference/rest/auth/#section-sign-in-anonymously

    let makePostRequest (url : string) (requestBody : string) = 
    let req = WebRequest.CreateHttp url
    req.CookieContainer <- new CookieContainer()
    req.Method <- "POST"
    req.ProtocolVersion <- HttpVersion.Version10
    let postBytes = requestBody |> System.Text.Encoding.ASCII.GetBytes
    req.ContentLength <- postBytes.LongLength
    req.ContentType <- "application/xml; charset=utf-8"
    async{
        use! reqStream = req.GetRequestStreamAsync() |> Async.AwaitTask
        do! reqStream.WriteAsync(postBytes, 0, postBytes.Length) |> Async.AwaitIAsyncResult |> Async.Ignore
        reqStream.Close()
        use! res = req.AsyncGetResponse() 
        use stream = res.GetResponseStream()
        use reader = new StreamReader(stream)
        let! rdata = reader.ReadToEndAsync() |> Async.AwaitTask        
        return rdata
    }

我这样称呼它:

    let url = "https://www.googleapis.com/identitytoolkit/v3/relyingparty/signupNewUser?key=XXXXXXXXXXXXXXXXX"
    let data = "returnSecureToken=true"
    makePostRequest url data

我是个新手 F级# 还有一点困惑,这是怎么回事。如何从该请求中获取JSON响应?我怎么知道这是什么时候完成的?这会阻止主线程上的UI吗?我正在翻译以下Swift代码块:

 Auth.auth().signInAnonymously(completion: { (user, error) in

        if let err = error {
            print(err.localizedDescription)
            return
        }

    })

这里的一切对我来说都是有意义的,因为我们有一个完成块,它在方法执行完成后被调用,我们知道 user 变量将包含从服务器获得的响应,在F#中对我来说意义不大。

更新:

根据注释中的建议,我引用了F#Data:HTTP实用程序,并创建了以下代码段:

let url = "https://www.googleapis.com/identitytoolkit/v3/relyingparty/signupNewUser?key=XXXXXXXXXXXX"
Http.RequestString
    ( url, 
      headers = [ ContentType HttpContentTypes.Json ],
      body = TextRequest """ {"returnSecureToken": true} """)

但是,这会产生错误 The value, namespace, type or module Http is not defined

更新2: 我已接受以下代码:

let fetchUrl callback url (requestBody : string) =        
    let req = WebRequest.Create(Uri(url)) 
    req.Method <- "POST"
    let postBytes = requestBody |> System.Text.Encoding.ASCII.GetBytes
    req.ContentLength <- postBytes.LongLength
    req.ContentType <- "application/json; charset=utf-8"
    let reqStream = req.GetRequestStream() 
    reqStream.Write(postBytes, 0, postBytes.Length);
    reqStream.Close()

    use resp = req.GetResponse() 
    use stream = resp.GetResponseStream() 
    use reader = new IO.StreamReader(stream) 
    callback reader url

let myCallback (reader:IO.StreamReader) url = 
    let html = reader.ReadToEnd()
    let html1000 = html.Substring(0,1000)
    printfn "Downloaded %s. First 1000 is %s" url html1000
    html      // return all the html


let openLandlord ()  =
    let url = "https://www.googleapis.com/identitytoolkit/v3/relyingparty/signupNewUser?key=XXXXXXXXXXXXXXXXXXX"
    let requestBody = """ {"returnSecureToken": true} """
    fetchUrl myCallback url requestBody

以下示例:

https://fsharpforfunandprofit.com/posts/fvsc-download/

但是当我打电话给 openLandlord 此处的功能:

 override x.ViewDidLoad () =
    base.ViewDidLoad ()
    openLandlord ()

我得到以下错误:

此表达式应具有uint类型,但此处具有string类型。

错误:

1. 绑定中此点或之前的不完整结构化构造。
2. 未定义构造函数请求的值。
3. 成员定义中存在意外的关键字匹配。
4. 未定义值、命名空间、类型或模块响应。
5. 成员定义中标识了意外。