Asynchronous F#：处理web异常

我是编程新手，F#是我的第一语言

以下是我的代码的相关片段：

let downloadHtmlToDiskAsync (fighterHtmlDirectory: string) (fighterBaseUrl: string) (fighterId: int) = 
    let fighterUrl = fighterBaseUrl + fighterId.ToString()
    try 
        async {

            let! html = fetchHtmlAsync fighterUrl
            let fighterName = getFighterNameFromPage html

            let newTextFile = File.Create(fighterHtmlDirectory + "\\" + fighterId.ToString("00000") + " " + fighterName.TrimEnd([|' '|]) + ".html")
            use file = new StreamWriter(newTextFile) 
            file.Write(html) 
            file.Close()
        }
    with
        :? System.Net.WebException -> async {File.AppendAllText("G:\User\WebScraping\Invalid Urls.txt", fighterUrl + "\n")}

let downloadFighterDatabase (directoryPath: string) (fighterBaseUrl: string) (beginningFighterId: int) (endFighterId: int) =
    let allFighterIds = [for id in beginningFighterId .. endFighterId -> id]
    allFighterIds
    |> Seq.map (fun fighterId -> downloadHtmlToDiskAsync directoryPath fighterBaseUrl fighterId)
    |> Async.Parallel
    |> Async.RunSynchronously

我已经使用F#Interactive测试了fetchHtmlAsync和getFighterNameFromPage函数。他们都很好

但是，当我构建并运行解决方案时，会收到以下错误消息：

FSharp.Core.dll中发生类型为“System.Net.WebException”的未处理异常 其他信息：远程服务器返回错误：（404）未找到

---

出了什么问题？我应该做哪些更改？

将您的

放入
异步
中，然后尝试

let downloadHtmlToDiskAsync (fighterHtmlDirectory: string) (fighterBaseUrl: string) (fighterId: int) = 
    let fighterUrl = fighterBaseUrl + fighterId.ToString()
    async {
        try
            let! html = fetchHtmlAsync fighterUrl
            let fighterName = getFighterNameFromPage html

            let newTextFile = File.Create(fighterHtmlDirectory + "\\" + fighterId.ToString("00000") + " " + fighterName.TrimEnd([|' '|]) + ".html")
            use file = new StreamWriter(newTextFile) 
            file.Write(html) 
            file.Close()
        with
            :? System.Net.WebException -> File.AppendAllText("G:\User\WebScraping\Invalid Urls.txt", fighterUrl + "\n")
    }

哈哈，是的，我只是在你的回答上评论了完全相同的事情谢谢，阿尔伯特扬！原来我是个白痴。。。我最初是按照您的方式编写代码的，但由于我忘记重新生成解决方案，我不断收到一条错误消息，这促使我开始进行不必要和不准确的更改。现在我刚刚重建，一切都很顺利。再次感谢您的帮助。：-）这发生在我们当中最好的人身上：）