Rock-paper-scissors: Difference between revisions

=={{header|F#}}==

<lang FSharp>open System

let random = Random ()

let rand = random.NextDouble () //Gets a random number in the range (0.0, 1.0)

/// Union of possible choices for a round of rock-paper-scissors

type Choice =

| Rock

| Paper

| Scissors

/// Gets the string representation of a Choice

let getString = function

| Rock -> "Rock"

| Paper -> "Paper"

| Scissors -> "Scissors"

/// Defines rules for winning and losing

let beats (a : Choice, b : Choice) =

match a, b with

| Rock, Scissors -> true // Rock beats Scissors

| Paper, Rock -> true // Paper beats Rock

| Scissors, Paper -> true // Scissors beat Paper

| _, _ -> false

/// Generates the next move for the computer based on probability derived from previous player moves.

let genMove r p s =

let tot = r + p + s

let n = rand

if n <= s / tot then Rock

elif n <= (s + r) / tot then Paper

else Scissors

/// Gets the move chosen by the player

let rec getMove () =

printf "[R]ock, [P]aper, or [S]cissors?: "

let choice = Console.ReadLine ()

match choice with

| "r" | "R" -> Rock

| "p" | "P" -> Paper

| "s" | "S" -> Scissors

| _ ->

printf "Invalid choice.\n\n"

getMove ()

/// Place where all the game logic takes place.

let rec game (r : float, p : float, s : float) =

let comp = genMove r p s

let player = getMove ()

Console.WriteLine ("Player: {0} vs Computer: {1}", getString player, getString comp)

Console.WriteLine (

if beats(player, comp) then "Player Wins!\n"

elif beats(comp, player) then "Computer Wins!\n"

else "Draw!\n"

)

let nextR = if player = Rock then r + 1.0 else r

let nextP = if player = Paper then p + 1.0 else p

let nextS = if player = Scissors then s + 1.0 else s

game (nextR, nextP, nextS)

game(1.0, 1.0, 1.0)

</lang>