open System.IO

open System.Net

open Microsoft.FSharp.Control.WebExtensions

let getPage (url:string)  =

        async {

                let req = WebRequest.Create(url)

                let! res = req.AsyncGetResponse()

                use stream = res.GetResponseStream()

                use asyncReader = new AsyncStreamReader(stream)

                return! asyncReader.ReadToEnd()

        }

​

let webPages = 

    [ "https://forbiddenplanet.com/log/recommendations/50-sf-books-you-must-read/"

      "http://io9.com/14-tv-shows-that-reinvented-science-fiction-in-the-past-1714350217"

    ]

    |> List.map getPage

    |> Async.Parallel

    |> Async.RunSynchronously

​

webPages 

|> Array.map(String.length)

|> Array.iter(printfn "%A")