MeasureUnit.scala

package aux

object Scaladores extends App {

  implicit class AddOf(val num : Int) extends AnyVal {
    def of[T <: MeasureUnit] = Value[T](num)
  }

  trait MeasureUnit
  trait x[A <: MeasureUnit, B <: MeasureUnit] extends MeasureUnit
  trait /[A <: MeasureUnit, B <: MeasureUnit] extends MeasureUnit
  class m extends MeasureUnit
  class km extends MeasureUnit
  class cm extends MeasureUnit
  class s extends MeasureUnit

  case class Value[T <: MeasureUnit](num : Int) extends AnyVal {
    def *[O <: MeasureUnit](other : Value[O]) = Value[T x O](num * other.num)
    def as[O <: MeasureUnit](implicit conversor : Conversor[T, O]) : Value[O] =
      conversor.converte(this)
    def as[O <: MeasureUnit, K <: MeasureUnit](implicit conversor : Conversor[T, K],
                                               converso : Conversor[K, O]) : Value[O] =
      converso.converte(conversor.converte(this))
  }

  abstract class Conversor[F <: MeasureUnit, T <: MeasureUnit](fator : Int) {
    def converte(f : Value[F]) : Value[T] = Value[T](f.num * fator)
  }

  implicit object FromKMtoM extends Conversor[km, m](1000)
  implicit object FromMtoCm extends Conversor[m, cm](100)
  implicit object FromMMtoCmCM extends Conversor[m x m, cm x cm](10000)

  type `m/s^2` = m / (s x s) // /[m, x[s, s]] problema!
  type `m/s^2 2` = (m / s) / s // /[/[m, s], s] problema!

  val a = 2.of[m]
  println(a)
  println(a.as[cm])

  val b : Value[m x m] = 2.of[m] * 2.of[m]
  println(b)
  println(b.as[cm x cm])

  val c = 2.of[km]
  println(c)
  println(c.as[cm, m])

}