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trait Day
object Test {
def foo(t: Int with Day) = t == t
}
class DayOps(val i: Int with Day) extends AnyVal
case class Test1(d: Int with Day)
case class Test2(d1: Int with Day, d2: Int with Day)
class User
class Checkin
object Example {
type Tagged[U] = { type Tag = U }
type @@[T, U] = T with Tagged[U] // Thanks to @retronym for suggesting this type alias
class Tagger[U] {
def apply[T](t : T) : T @@ U = t.asInstanceOf[T @@ U]
}
def tag[U] = new Tagger[U]
// Manual specialization needed here ... specializing apply above doesn't help
def tag[U](i : Int) : Int @@ U = i.asInstanceOf[Int @@ U]
def tag[U](l : Long) : Long @@ U = l.asInstanceOf[Long @@ U]
def tag[U](d : Double) : Double @@ U = d.asInstanceOf[Double @@ U]
def fetch[A](id: Int @@ A): A = null.asInstanceOf[A]
def tag[U](arr: Array[Int]):Array[Int @@ U] = arr.asInstanceOf[Array[Int @@ U]]
tag[User](Array(3, 4, 5)).map(_.toString)
}
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