Closures

object Main {
  def main(args: Array[String]): Unit = {
    val factor = 3
    val multiply = (x: Int) => x * factor
    println(multiply(5))
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val greeting = "Hello"
    val greet = (name: String) => s"$greeting, $name!"
    println(greet("Ann"))
    println(greet("Bob"))
  }
}

object Main {
  def makeAdder(n: Int): Int => Int = x => x + n
  def main(args: Array[String]): Unit = {
    val add10 = makeAdder(10)
    val add100 = makeAdder(100)
    println(add10(5))
    println(add100(5))
  }
}

object Main {
  def prefixer(p: String): String => String = s => p + s
  def main(args: Array[String]): Unit = {
    val withDr = prefixer("Dr. ")
    val withMr = prefixer("Mr. ")
    println(withDr("Smith"))
    println(withMr("Jones"))
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    var count = 0
    val increment = () => { count += 1; count }
    println(increment())
    println(increment())
    println(increment())
  }
}

object Main {
  def counter(): () => Int = {
    var n = 0
    () => { n += 1; n }
  }
  def main(args: Array[String]): Unit = {
    val c1 = counter()
    val c2 = counter()
    println(c1())
    println(c1())
    println(c2())
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    var msg = "first"
    val show = () => println(msg)
    show()
    msg = "second"
    show()
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val taxRate = 0.2
    val withTax = (price: Double) => price * (1 + taxRate)
    println(withTax(100))
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val threshold = 3
    val nums = List(1, 2, 3, 4, 5)
    val big = nums.filter(_ > threshold)
    println(big)
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val fns = for (i <- 1 to 3) yield () => i
    println(fns.map(f => f()))
  }
}

object Main {
  def discounter(rate: Double): Double => Double = price => price * (1 - rate)
  def main(args: Array[String]): Unit = {
    val sale = discounter(0.25)
    println(sale(80))
    println(sale(200))
  }
}