Dependent Types

dependent-types.scala

trait DependentValue{
  type V
  val value: V
}

//object DependentValue {
//  def apply[A](a: A): DependentValue { type V = A } = new DependentValue {
//    type V = A
//    val value = a
//  }
//}

object DependentValue {
  trait Aux[A] extends DependentValue { type V = A }

  def apply[A](a: A): DependentValue.Aux[A] = new Aux[A] {
    val value = a
  }
}

def magic(input: DependentValue): DependentValue = input.value

val dep1: DependentValue.Aux[Int] = DependentValue(1)
val depTwo = DependentValue("two")

val intReturnValue: Int = magic(dep1)
val stringReturnValue: String = magic(depTwo)