9e8a12f2112b / MaybeDivideable2

MaybeDivideable2.scala

sealed trait MaybeDivideable {
  def get: Int
  def flatMap(f: Int => MaybeDivideable): MaybeDivideable
  
  /* New map method */
  def map(f: Int => Int): MaybeDivideable
}

case class Divideable(value: Int) extends MaybeDivideable {
  require(value != 0, "value must not be 0")

  override def get: Int = value
  override def flatMap(f: Int => MaybeDivideable): MaybeDivideable = f(get)
  
  /* New map method */
  override def map(f: Int => Int): MaybeDivideable = MaybeDivideable(f(get))
}

case object UnDivideable extends MaybeDivideable {
  override def get: Int = throw new NoSuchFieldException
  override def flatMap(f: Int => MaybeDivideable): MaybeDivideable = UnDivideable
  
  /* New map method */
  override def map(f: Int => Int): MaybeDivideable = UnDivideable
}

object MaybeDivideable {
  def apply(value: Int): MaybeDivideable =
    if (value == 0) UnDivideable else Divideable(value)
}