Value classes example

values.scala

class Meter(val value: Double) extends AnyVal {
  def toFeet = new Feet(value * 3.281)
}
class Feet(val value: Double) extends AnyVal {
  def toMeter = new Meter(value / 3.281)
}

object Example {
  def convert(meter: Meter): Feet = {
    meter.toFeet
  }
}