zdk.fs

open System

type Sound = Z | D | K
with
  override this.ToString() =
    match this with
    | Z -> "ズン"
    | D -> "ドコ"
    | K -> "キ・ヨ・シ！"

let rnd = Random()
let genSound () = [|Z;D|].[rnd.Next(2)]

let rec loop x = function
| D::Z::Z::Z::Z::_ as xs -> printfn "%s" (string K)
| xs -> printf "%s" (string x); loop (genSound ()) (x::xs)

[<EntryPoint>]
let main _ =
  loop (genSound ())
  0