gistfile1.fs

open System
open System.Net
open System.Text
open System.IO

let siteRoot = @"D:\mySite\"
let host = "http://localhost:8080/"

let listener (handler:(HttpListenerRequest -> HttpListenerResponse -> Async<unit>)) cancellationToken =
    let hl = new HttpListener()
    hl.Prefixes.Add host
    hl.Start()
    let task = Async.FromBeginEnd(hl.BeginGetContext, hl.EndGetContext)
    let loop = 
        async {
            while true do
                let! context = task
                Async.Start(handler context.Request context.Response)
        }
    Async.Start(loop, cancellationToken)

let output (req:HttpListenerRequest) =
    let file = Path.Combine(siteRoot, 
                            Uri(host).MakeRelativeUri(req.Url).OriginalString)
    printfn "Requested : '%s'" file
    if (File.Exists file)
        then File.ReadAllText(file)
        else "File does not exist!"

let cancellableWork = new System.Threading.CancellationTokenSource()
listener (fun req resp ->
    async {
        let txt = Encoding.ASCII.GetBytes(output req)
        resp.ContentType <- "text/html"
        resp.OutputStream.Write(txt, 0, txt.Length)
        resp.OutputStream.Close()
    })
    cancellableWork.Token

cancellableWork.Cancel()