F#プログラミングメモ #3

私も同期版と非同期版のHTTPクライアントを書いてみた。洗練はこれから。

// FSharp-2.0.0.0
open System.IO;;
open System.Net;;

let getTitle (html : string) =
    let startPos = html.IndexOf("<title>")+7 in
    let endPos   = html.IndexOf("</title>") in
    let title = html.Substring(startPos, endPos - startPos) in
    title;;

// 同期版
let SyncHttp (url:string) =
  let req = WebRequest.Create(url)
#if use_proxy
  req.Proxy <- new WebProxy("http://10.0.xx.xx:8080")
#endif
  use rsp = req.GetResponse() in
  use stream = rsp.GetResponseStream() in
  use reader = new StreamReader(stream) in
  let html = reader.ReadToEnd() in
  getTitle(html) |> printfn "SyncHttp [%s]";;

let pages = 
    [| 
    SyncHttp "http://www.google.co.jp/";
    SyncHttp "http://news.google.co.jp/nwshp?hl=ja&tab=wn";
    SyncHttp "http://www.yahoo.co.jp/";
    |];;

// 非同期版
type System.Net.WebRequest with
  member x.GetResponseAsync() =
    Async.FromBeginEnd(x.BeginGetResponse, x.EndGetResponse)

let AsyncHttp (url:string) =
  async { let  req = WebRequest.Create(url) in
#if use_proxy
          req.Proxy <- new WebProxy("http://10.0.xx.xx:8080")
#endif
          let! rsp = req.GetResponseAsync() in
          use stream = rsp.GetResponseStream() in
          use reader = new StreamReader(stream) in
          let html = reader.ReadToEnd() in
          getTitle(html) |> printfn "AsyncHttp [%s]"
  };;

let Sleeping n =
    async { do! Async.Sleep(n)
            printfn "timeount %d ms" n
    };;

Async.RunSynchronously ( AsyncHttp "http://www.google.com"; )

Async.RunSynchronously ( Async.Parallel [ Sleeping(2000);
                    AsyncHttp "http://www.google.com";
                    AsyncHttp "http://news.google.co.jp/nwshp?hl=ja&tab=wn";
                    AsyncHttp "http://www.yahoo.co.jp/";
                    Sleeping(1000);
     ]);;

実行結果

SyncHttp [Google]
SyncHttp [Google ニュース]
SyncHttp [Yahoo! JAPAN]
AsyncHttp [Google]
AsyncHttp [Yahoo! JAPAN]
AsyncHttp [Google ニュース]
AsyncHttp [Google]
timeount 1000 ms
timeount 2000 ms