AlgebraicDataTypes.scala

package scalabeginner.algebraicdatatypes

object AlgebraicDataTypes extends App {

  //Sum ADT
  sealed abstract trait Month
  case object January extends Month
  case object February extends Month
  case object March extends Month
  case object April extends Month
  case object May extends Month
  case object June extends Month
  case object July extends Month
  case object August extends Month
  case object September extends Month
  case object October extends Month
  case object November extends Month
  case object December extends Month

  object Month {
    def toInt(month: Month): Int =
      month match {          // exhaustive matching possible due to sealed trait
        case January => 1
        case February => 2
        case March => 3
        case April => 4
        case May => 5
        case June => 6
        case July => 7
        case August => 8
        case September => 9
        case October => 10
        case November => 11
        case December => 12
        case _ => 0
      }

  }

  val thisMonth:Month = November
  println(thisMonth)
  val monthNum = Month.toInt(thisMonth)
  println(monthNum)


  //Product ADT
  sealed case class RGB(red: Int, green: Int, blue: Int)
  val magenta = RGB(10,200,255)

  //Hybrid
  case class Point(x: Double, y: Double)
  sealed abstract trait Shape
  case class Circle(centre: Point, radius: Double) extends Shape
  case class Rectangle(topLeft: Point, height: Double, width:Double) extends Shape

  object Shape {
    def area(shape: Shape): Double =
      shape match {
        case Circle(Point(x, y), radius) => Math.PI *
          Math.pow(radius, 2)
        case Rectangle(_, h, w) => h * w
      }
  }

  val circleArea = Shape.area(Circle(Point(0,0),10))
  val rectangle = Rectangle(Point(6, 7), 10, 10)
  val rectangleArea = Shape.area(rectangle)
  println(circleArea)
  println(rectangleArea)

}