Yeni Türler

Tür Güvenli Sarmalayıcılar

case class UserId(value: Int)
case class ProductId(value: Int)

object Main:
  def main(args: Array[String]): Unit =
    val u = UserId(1)
    val p = ProductId(1)
    println(u.value == p.value) // values equal, types differ

İlkel Tür Saplantısı Sorunu

case class Email(value: String)
case class City(value: String)

object Main:
  def greet(c: City): String = s"Welcome to ${c.value}"

  def main(args: Array[String]): Unit =
    println(greet(City("Berlin")))

Durum Sınıfı Yeni Türleri

case class OrderId(value: String)

object Main:
  def main(args: Array[String]): Unit =
    val id = OrderId("ORD-42")
    println(id)
    println(id.value)

Opak Tür Yeni Türleri

object Ids:
  opaque type UserId = Int
  def apply(i: Int): UserId = i
  extension (u: UserId) def value: Int = u

object Main:
  def main(args: Array[String]): Unit =
    val u = Ids(7)
    println(u.value)

Uzantılarla Davranış Ekleme

object Money:
  opaque type Cents = Long
  def apply(n: Long): Cents = n
  extension (c: Cents)
    def +(o: Cents): Cents = c + o
    def toDollars: Double = c / 100.0

object Main:
  def main(args: Array[String]): Unit =
    val total = Money(250) + Money(750)
    println(total.toDollars)

İşlev İmzalarında Yeni Türler

case class Width(value: Int)
case class Height(value: Int)

object Main:
  def area(w: Width, h: Height): Int = w.value * h.value

  def main(args: Array[String]): Unit =
    println(area(Width(4), Height(5)))

Yeni Türler ve Koleksiyonlar

case class UserId(value: Int)

object Main:
  def main(args: Array[String]): Unit =
    val names = Map(UserId(1) -> "Ada", UserId(2) -> "Bob")
    println(names(UserId(2)))

Doğrulanmış Yeni Türler

case class NonEmptyString private (value: String)
object NonEmptyString:
  def of(s: String): Option[NonEmptyString] =
    if s.nonEmpty then Some(NonEmptyString(s)) else None

object Main:
  def main(args: Array[String]): Unit =
    println(NonEmptyString.of("hi"))
    println(NonEmptyString.of(""))

Gösterim Seçme

object Temp:
  opaque type Kelvin = Double
  def apply(d: Double): Kelvin = d
  extension (k: Kelvin) def value: Double = k

object Main:
  def main(args: Array[String]): Unit =
    val readings = List(Temp(300.0), Temp(310.5))
    println(readings.map(_.value).sum)

Yanlışlıkla Dönüştürmeleri Önleme

case class Meters(value: Double)
case class Feet(value: Double)

object Main:
  def toFeet(m: Meters): Feet = Feet(m.value * 3.281)

  def main(args: Array[String]): Unit =
    println(toFeet(Meters(2.0)))

Yeni Türler Ne Zaman Kullanılır

object Domain:
  opaque type Sku = String
  def of(s: String): Option[Sku] =
    if s.startsWith("SKU-") then Some(s) else None
  extension (k: Sku) def raw: String = k

object Main:
  def main(args: Array[String]): Unit =
    println(Domain.of("SKU-9").map(_.raw))

Kısa Kontrol

Özet

object Ids:
  opaque type AccountId = Long
  def apply(n: Long): AccountId = n
  extension (a: AccountId) def value: Long = a

object Main:
  def main(args: Array[String]): Unit =
    val acc = Ids(1001L)
    println(acc.value)