My training.Translating C# code to F#.

C# to F# 2.fs

(*
My training.Translating C# code to F#.
http://www.fincher.org/tips/Languages/csharp.shtml
*)
open System
open System.IO
open System.Net



// Console.WriteLine test
let k = 35
Console.WriteLine("k={0,-4}.",k) // k=35  .
Console.WriteLine("k={0,4}.",k) // k=  35.
Console.WriteLine("k={0:X}.",k) // k=23.
Console.WriteLine("k={0:X4}.",k) // k=0023.

// TODO: How to write extended method?
// Console.WriteLine(123.ToString("#,#0"))

// This code offers key input after every expression evaluated.
Console.ReadKey() |> ignore



// F. example of virtual functions
// Plane is a class contains abstruct methods
type Plane() as this =
    [<DefaultValue>]
    val mutable X:int
    do this.X<-10
    abstract topSpeed : unit->double
    default this.topSpeed() = 300.0
type Jet() =
    inherit Plane()
    override x.topSpeed()=900.0

// TODO: couldn't assign base class instance.
// Is covariance not satisfied?
// let plane:Plane = new Jet()
let jet=new Jet()
Console.WriteLine("planes top speed:{0}",jet.topSpeed())



// Class with Property,explicit class,initializer
type Nirvana = class
    val mutable mySpeed : double
    // I don't know why but constructor requires curly brace
    new()={ mySpeed=300.00 }
    member x.TopSpeed
        with get() = x.mySpeed
        and set v = x.mySpeed <- v
end

let nirvana = Nirvana()
nirvana.TopSpeed <- 100.
printfn"%f" <| nirvana.TopSpeed



// I. Write the current time
printfn"%s"<|DateTime.Now.ToString()



// Couldn't write 
let mutable streamWriter = null
try
    streamWriter <- new StreamWriter(@"C:\sandbox\sample2.txt")
    streamWriter.WriteLine "This is first line"
    streamWriter.WriteLine "This is second line"
finally
    if streamWriter<>null then streamWriter.Close()



// download specified urls
let download(urls:string list) =
    for url in urls do
        let req = WebRequest.Create url
        let res = req.GetResponse()
        let stream = res.GetResponseStream()
        let reader = new StreamReader(stream,Encoding.ASCII)
        printfn"%s"<| reader.ReadToEnd()
download<| ["http://d.hatena.ne.jp/mclh46"]



// read html of my twitter
using(new WebClient())
    (fun client-> printfn"%A"<|client.DownloadString("http://twitter.com/#!/nagat01"))