अपारदर्शी प्रकार

object Distances:
  opaque type Meters = Double

object Main:
  def main(args: Array[String]): Unit =
    println("Opaque types compile to their underlying type")

object Distances:
  opaque type Meters = Double
  def meters(d: Double): Meters = d
  def toDouble(m: Meters): Double = m

object Main:
  def main(args: Array[String]): Unit =
    val d = Distances.meters(5.0)
    println(Distances.toDouble(d))

object Distances:
  opaque type Meters = Double
  def apply(d: Double): Meters = d
  def show(m: Meters): String = s"$m m"

object Main:
  def main(args: Array[String]): Unit =
    val m = Distances(10.0)
    println(Distances.show(m))

object Distances:
  opaque type Meters = Double
  def apply(d: Double): Meters = d
  extension (m: Meters)
    def +(other: Meters): Meters = m + other
    def value: Double = m

object Main:
  def main(args: Array[String]): Unit =
    val total = Distances(3.0) + Distances(4.0)
    println(total.value)

object Units:
  opaque type Meters = Double
  opaque type Kilometers = Double
  def m(d: Double): Meters = d
  def km(d: Double): Kilometers = d
  def toMeters(k: Kilometers): Meters = k * 1000

object Main:
  def main(args: Array[String]): Unit =
    val far = Units.km(2.0)
    println(Units.toMeters(far))

object Ids:
  opaque type UserId <: Int = Int
  def apply(i: Int): UserId = i

object Main:
  def main(args: Array[String]): Unit =
    val id = Ids(99)
    println(id + 1)

object Ages:
  opaque type Age = Int
  def of(i: Int): Option[Age] =
    if i >= 0 && i < 150 then Some(i) else None
  extension (a: Age) def value: Int = a

object Main:
  def main(args: Array[String]): Unit =
    println(Ages.of(30).map(_.value))
    println(Ages.of(-1))

object Temps:
  opaque type Celsius = Double
  def c(d: Double): Celsius = d
  extension (t: Celsius) def value: Double = t

object Main:
  def main(args: Array[String]): Unit =
    val readings = List(Temps.c(20.0), Temps.c(21.5))
    println(readings.map(_.value).sum)

object Demo:
  type Name = String          // transparent alias
  opaque type Email = String  // opaque
  def email(s: String): Email = s
  extension (e: Email) def raw: String = e

object Main:
  def main(args: Array[String]): Unit =
    val e = Demo.email("a@b.com")
    println(e.raw)

object Money:
  opaque type Cents = Long
  def cents(n: Long): Cents = n
  extension (c: Cents)
    def +(o: Cents): Cents = c + o
    def value: Long = c

object Main:
  def main(args: Array[String]): Unit =
    val total = Money.cents(150) + Money.cents(50)
    println(total.value)

object Geo:
  opaque type Latitude = Double
  def lat(d: Double): Option[Latitude] =
    if d >= -90 && d <= 90 then Some(d) else None
  extension (l: Latitude) def value: Double = l

object Main:
  def main(args: Array[String]): Unit =
    println(Geo.lat(41.0).map(_.value))

object Ids:
  opaque type OrderId = String
  def apply(s: String): OrderId = s
  extension (o: OrderId) def raw: String = o

object Main:
  def main(args: Array[String]): Unit =
    val id = Ids("ORD-1")
    println(id.raw)