CollectFirstBenchmarks.scala

package me.jeffshaw

import org.openjdk.jmh.annotations._
import scala.annotation.tailrec

@State(Scope.Benchmark)
class CollectFirstBenchmarks {

  val values = List.tabulate(1000)(identity)

  def trivialPredicate(i: Int): Option[String] = {
    None
  }

  def expensivePredicate(i: Int): Option[String] = {
    List.tabulate(i)(Math.pow(_, 3)).find(_ == -1.0D).map(_.toString)
  }

  @tailrec
  final def jimka[A, B](domain:List[A], f: A=>Option[B]): Option[B] = {
    domain match {
      case Nil => None
      case d::tail => {
        f(d) match {
          case None => jimka(tail,f)
          case found => found
        }
      }
    }
  }

  def jducoeur[A, B](domain: List[A], f: A => Option[B]): Option[B] = {
    domain.collectFirst(Function.unlift(f))
  }

  @Benchmark
  def benchmarkTrivialJimka(): Option[String] = {
    jimka(values, trivialPredicate)
  }

  @Benchmark
  def benchmarkTrivialJducoeur(): Option[String] = {
    jducoeur(values, trivialPredicate)
  }

  @Benchmark
  def benchmarkExpensiveJimka(): Option[String] = {
    jimka(values, expensivePredicate)
  }

  @Benchmark
  def benchmarkExpensiveJducoeur(): Option[String] = {
    jducoeur(values, expensivePredicate)
  }
}