Dark Syntax Sugar

Single Abstract Method

trait Action {
  def act(x: Int): Unit
}

// 다음과 같이 사용해야 하지만
val action: Action = new Action {
  override def act(x: Int): Unit = println(x)
}

// 아래와 같이 표현하는 것도 가능
val action: Action = (x: Int) => println(x)

// 비슷하게 아래와 같이 Thread 생성 가능
val thread: Thread = new Thread(() => println("run"))

 

Methods with ':' are special

class MyStream[T] {
  def -->:(value: T): MyStream[T] = ???
}

val stream = 1 -->: 2 -->: new MyStream[Int]

 

Infix Generic Types

trait <[A, B]
def lessThan[A, B]: A < B = ???

 

Rewrite to Update

val arr = Array(1, 2, 3)
arr(2) = 7 // arr.update(2, 7)
arr.foreach(println) // 1 2 7

 

Setters for Mutable Types

class Mutable {
  private var internalMember: Int = 0
  def member: Int                 = internalMember
  def member_=(value: Int): Unit  = internalMember = value
}

val mutable = new Mutable
mutable.member = 3
println(mutable.member) // 3

 

Unary Operator

class MyString(value: String)  {
  def unary_! : String = value.reverse
}

val s = new MyString("abcd")
val reverse = !s
println(reverse) // dcba

 

참고: https://www.udemy.com/course/advanced-scala/