Conway's Game of Life in Scala

ForScalaJS.scala

import org.scalajs.dom

// Paste here http://www.scala-js-fiddle.com/
// Ctrl-enter to recompile

@JSExport
object ScalaJSExample{
  
  type Coord = Pair[Int, Int]
  type CoordSet = Set[Coord]
 
  def handleString(str: String, identity:Boolean=false): String = {
 
    val lines=str.stripMargin.trim.split("\n")
    
    val coords: CoordSet = for (
      (line, x) <- lines.zipWithIndex toSet;
      (ch, y) <- line.zipWithIndex if (ch == '*')
    ) yield (x, y)
 
    
    def nextGen(coords: CoordSet): CoordSet = {
      def getCube(c: Coord): CoordSet = {
        for (dx <- Set(-1, 0, 1);dy <- Set(-1, 0, 1))
          yield (c._1 + dx, c._2 + dy)        
      }
         // coords flatMap getCube gets us our search set, i.e. area around existing points
      coords flatMap getCube filter
      	 {coord=>val numNeigh = getCube(coord)-coord count coords;
      	  (numNeigh == 3 || numNeigh == 2 && coords(coord))} toSet      
    }
 
    def toString(coords: CoordSet): String ={
      val sx = lines.size
      val sy = lines.map(_.size).max
      Seq.tabulate(sx, sy)((x,y) => if (coords((x, y))) "*" else ".").map(_.mkString).mkString("\n")
    } 
 
    toString(if (identity) coords else nextGen(coords))
  }
  
  val toad2="""..........
    |...*.......
    |.*..*......
    |.*.**......
    |..*........
    |....*......
    |...........
    """   
  
  val sandbox = dom.document
    .getElementById("canvas")
    .asInstanceOf[dom.HTMLCanvasElement]

  val renderer = sandbox.getContext("2d")
    .asInstanceOf[dom.CanvasRenderingContext2D]

  val (w, h) = (sandbox.height.toDouble, sandbox.height.toDouble)
  
  var current=(handleString(toad2,true))
  
  @JSExport
  def main(args: Array[String]): Unit = {
    dom.setInterval(() => {
      
       renderer.fillStyle = s"white"
      // renderer.fillRect(1, 1, 20, 20)
      renderer.clearRect(0,0,w,h)
       for ((line,idx)<-current.split("\n").zipWithIndex){
         renderer.fillText(line.map(_+"  ").mkString,200,200+idx*20)
       }
       current=handleString(current)
    }, 1000 // make this smaller to speed up
    )
  }
}
    

GameOfLife.scala

package playpen

// Check with this http://projects.abelson.info/life/

object GameOfLife extends App {

  type Coord = Pair[Int, Int]
  type CoordSet = Set[Coord]

  def handleString(str: String, identity:Boolean=false): String = {

    val lines=str.stripMargin.trim.split("\n")
    
    val coords: CoordSet = for (
      (line, x) <- lines.zipWithIndex toSet;
      (ch, y) <- line.zipWithIndex if (ch == '*')
    ) yield (x, y)

    
    def nextGen(coords: CoordSet): CoordSet = {
      def getCube(c: Coord): CoordSet = {
        for (dx <- Set(-1, 0, 1);dy <- Set(-1, 0, 1))
          yield (c._1 + dx, c._2 + dy)        
      }
         // coords flatMap getCube gets us our search set, i.e. area around existing points
      coords flatMap getCube filter
      	 {coord=>val numNeigh = getCube(coord)-coord count coords;
      	  (numNeigh == 3 || numNeigh == 2 && coords(coord))} toSet      
    }

    def toString(coords: CoordSet): String ={
      val sx = lines.size
      val sy = lines.map(_.size).max
      Seq.tabulate(sx, sy)((x,y) => if (coords((x, y))) "*" else ".").map(_.mkString).mkString("\n")
    } 

    toString(if (identity) coords else nextGen(coords))
  }                                             
  
      val toad="""......
    |...*..
    |.*..*.
    |.*..*.
    |..*...
    |......
    """                                           
    
    val block="""....
    |.**.
    |.**.
    |...."""                                     
    
      val toad2="""......
    |...*..
    |.*..*.
    |.*.**.
    |..*...
    |....*.
    """   
        
     val glider=""".*...
       |..*..
       |***..
       |....."""
      
  val start=toad2                                
  
  var current=start  
  println(handleString(current,true))
  println
      
  for (loop<-0 to 11){
   current=handleString(current)
   println(loop+1)
   println(current)  
  }                                

}