Reimplementation od Monty Hall problem in F#

MontyHall.fsx

let _rnd = System.Random()
let rand min max = _rnd.Next(min, max)

type Choice = | Yes | No

let addDoors = function
    | (1, _) -> [| "dragon"; "goat"; "goat" |]
    | (0, 1) -> [| "goat"; "dragon"; "goat" |]
    | (0, 0) -> [| "goat"; "goat"; "dragon" |]
    | (_, _) -> failwith "Option is out of range"

let openGoatDoor (doors: string array) =
    let rec impl d =
        match doors.[d] with
        | "goat" -> d
        | _ -> rand 0 3 |> impl
    rand 0 3 |> impl

let montyHall switch doorNumber =
    let doors = (rand 0 2, rand 0 2) |> addDoors
    let rec openNotChoosenGoatDoor() =
        match openGoatDoor doors with
        | x when x = doorNumber -> openNotChoosenGoatDoor()
        | x -> x
    let goatDoor = openNotChoosenGoatDoor()
    let nr =
        match switch with
        | No -> doorNumber
        | _ -> Set.ofList [0 .. 2] - Set.ofList [goatDoor; doorNumber] |> Seq.exactlyOne
    doors.[nr]

let testMontyHall playtimes switch =
    [0 .. playtimes]
    |> Seq.map (fun _ -> rand 0 3 |> montyHall switch)
    |> Seq.countBy id
    |> Seq.iter (printfn "%A")

testMontyHall 1000000 Yes

Pro srovnání imperativní implementace v Pythonu https://coderwall.com/p/fezbpa