为什么 F# 代码产生与 C# 不同的结果

Question

How come that this C# code works, but not the equivalent F# version (run through F# interactive)? Result should be an HTML table with figures only.

C# VERSION:

    var url = "https://www.investing.com/instruments/HistoricalDataAjax";

    var httpRequest = (HttpWebRequest)WebRequest.Create(url);
    httpRequest.Method = "POST";

    httpRequest.Headers["Origin"] = "http://www.investing.com";
    httpRequest.Headers["X-Requested-With"] = "XMLHttpRequest";
    httpRequest.ContentType = "application/x-www-form-urlencoded";
    httpRequest.UserAgent = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/51.0.2704.79 Chrome/51.0.2704.79 Safari/537.36";

    var data = "curr_id=1073048&smlID=2627117&header=SE0010296574%20Historical%20Data&st_date=04%2F12%2F2020&end_date=05%2F12%2F2021&interval_sec=Daily&sort_col=date&sort_ord=DESC&action=historical_data";

    using (var streamWriter = new StreamWriter(httpRequest.GetRequestStream()))
    {
        streamWriter.Write(data);
    }

    var httpResponse = (HttpWebResponse)httpRequest.GetResponse();
    using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
    {
        var result = streamReader.ReadToEnd();
        Console.WriteLine(result);
    }

    Console.WriteLine(httpResponse.StatusCode);

F# VERSION:

let url = "https://www.investing.com/instruments/HistoricalDataAjax"
let httpRequest = WebRequest.Create(url) :?> HttpWebRequest
httpRequest.Method <- "POST"
httpRequest.Headers.["Origin"] <- "http://www.investing.com"
httpRequest.UserAgent <- "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/51.0.2704.79 Chrome/51.0.2704.79 Safari/537.36"
httpRequest.Headers.["X-Requested-With"] <- "XMLHttpRequest"
httpRequest.ContentType <- "application/x-www-form-urlencoded"
let data = "curr_id=1073048&smlID=2627117&header=SE0010296574%20Historical%20Data&st_date=04%2F12%2F2020&end_date=05%2F12%2F2021&interval_sec=Daily&sort_col=date&sort_ord=DESC&action=historical_data";
let streamWriter = new StreamWriter(httpRequest.GetRequestStream())
streamWriter.Write(data)
let httpResponse = httpRequest.GetResponse() :?> HttpWebResponse
let streamReader = new StreamReader(httpResponse.GetResponseStream())
let html = streamReader.ReadToEnd()
printfn "%A" httpResponse.StatusCode

Answer 1

(Updated)

You get different results because the POST is sent without the body. The stream writer needs to flushed:

( use streamWriter = new StreamWriter(httpRequest.GetRequestStream())
  streamWriter.Write(data) )