(F#) 비동기 프로그래밍

async는 delay 개념이다.

use!, let!, do!는 force 개념이다.

 

예제:

 
open System.Net
open System.IO
 
let wgetAsync url =
    async { let request = WebRequest.Create (url:string)
            use! response = request.AsyncGetResponse()
            use responseStream = response.GetResponseStream()
            use reader = new StreamReader(responseStream)
            return reader.ReadToEnd() }
 
let urls = ["http://www.rosettacode.org/"; "http://www.yahoo.com/"; "http://www.google.com/"]
let content = urls
              |> List.map wgetAsync
              |> Async.Parallel
              |> Async.RunSynchronously

(출처: HTTP - Rosetta Code)

에서

use! response = request.AsyncGetResponse()

는

use response = request.GetResponse()

와 동일하다.