gistfile1.scala

package main

object Main {
  trait Thing[A] {
    def f(a: Int): A
  }

  def g[A: Thing](i: Int): A = implicitly[Thing[A]].f(i)
  def g[A](i: Int, f: Int => A): A = f(i)

  case class Example(x: Int)
  object Example {
    implicit val thing = new Thing[Example] {
      def f(a: Int): Example = Example(a / 2)
    }
  }

  def time[A](f: => A): A = {
    val t0 = System.nanoTime()
    val result = f
    val t1 = System.nanoTime()
    println("Elapsed time: " + (t1 - t0))
    result
  }

  def main(args: Array[String]): Unit = {

    val max = Int.MaxValue
    val seq = 0 until max
    def f(a: Int): Example = Example(a / 2)

    for (i <- seq) {
      i * 2
    }

    // explicit
    time {
      for (i <- seq) {
        g(i, x => Example(x / 2))
      }
    }

    // explicit (no anon)
    // time {
    //   for (i <- seq) {
    //     g(i, f)
    //   }
    // }

    // implicit
    // time {
    //   for (i <- seq) {
    //     g[Example](i)
    //   }
    // }
  }
}