Rock-paper-scissors: Difference between revisions

Here's another code: (I refactored the above code, it is more functional, more testable )

<lang Scala>object RockPaperScissors extends App {

def beats = Map(

'rock -> Set('lizard, 'scissors),

'paper -> Set('rock, 'spock),

'scissors -> Set('paper, 'lizard),

'lizard -> Set('spock, 'paper),

'spock -> Set('scissors, 'rock)

)

// init with uniform probabilities

def initPlayed = beats.mapValues(_ => 1)

def input = Symbol(readLine(s"""Your move (${beats.keys mkString ", "}): """))

def random(max: Int) = scala.util.Random.nextInt(max)

def display(text: String) = print(text)

def weighted(todo: Iterator[(Symbol,Int)], rand: Int, accum: Int = 0): Symbol = todo.next match {

case (s, i) if rand <= (accum + i) => s

case (_, i) => weighted(todo, rand, accum + i)

}

def calcMyMove(random: Int => Int, played: Map[Symbol,Int]) = {

weighted(played.toIterator, 1 + random(played.values.sum)) match {

// choose an opponent that would beat the player's anticipated move

case h => beats.find{case (s, l) => l contains h}.getOrElse(beats.head)._1

}

}

case class Result(text: String, won: Int, lost: Int, drew: Int) {

override def toString = s"$text. Won: $won, Lost: $lost, Drew: $drew"

}

def getResult(userWeapon: Symbol, myMove: Symbol, result: Result) = {

(userWeapon, myMove) match {

case (userWeapon, myMove) if beats(userWeapon) contains myMove =>

result.copy(text = "You won", won = result.won + 1)

case (userWeapon, myMove) if beats(myMove) contains userWeapon =>

result.copy(text = "You lost", lost = result.lost + 1)

case _ => result.copy(text = "We drew", drew = result.drew + 1)

}

}

def play(input: => Symbol, display: String => Unit, random: Int => Int)

(played: Map[Symbol,Int], result: Result): Result = {

val userWeapon = input

if (userWeapon != Symbol("")) {

val newResult = if (beats contains userWeapon) {

val myMove = calcMyMove(random, played)

display(s" My move: $myMove\n ")

getResult(userWeapon, myMove, result)

} else {

result.copy(text = " Unknown weapon, try again")

}

display(newResult + "\n")

play(input, display, random)(played get userWeapon match {

case None => played

case Some(count) => played.updated(userWeapon, count + 1)

}, newResult)

}

result

}

override def main(args: Array[String]): Unit =

play(input, display, random)(initPlayed, Result("Start", 0, 0, 0))

}</lang>

{{out}}

<pre>

Your move ('spock, 'rock, 'lizard, 'paper, 'scissors): rock

My move: 'rock

We drew. Won: 0, Lost: 0, Drew: 1

Your move ('spock, 'rock, 'lizard, 'paper, 'scissors): spock

My move: 'spock

We drew. Won: 0, Lost: 0, Drew: 2

Your move ('spock, 'rock, 'lizard, 'paper, 'scissors): lizard

My move: 'spock

You won. Won: 1, Lost: 0, Drew: 2

Your move ('spock, 'rock, 'lizard, 'paper, 'scissors): scissors

My move: 'spock

You lost. Won: 1, Lost: 1, Drew: 2

Your move ('spock, 'rock, 'lizard, 'paper, 'scissors): scissors

My move: 'spock

You lost. Won: 1, Lost: 2, Drew: 2

Your move ('spock, 'rock, 'lizard, 'paper, 'scissors): spock

My move: 'rock

You won. Won: 2, Lost: 2, Drew: 2</pre>