PimpMyPredicate.scala

package org.example

case class PimpMyPredicate[A](f: A => Boolean) {
  def &&(g: A => Boolean): A => Boolean = a => g(a) && f(a)
}

object PimpMyPredicate {
  implicit def enrichPredicate[A](f: A => Boolean): PimpMyPredicate[A] = PimpMyPredicate(f)
}

object Main {

  import PimpMyPredicate._

  val isNegative: Int => Boolean = _ < 0

  val isEven: Int => Boolean = _ % 2 == 0

  def main(args: Array[String]) {
    println(List(1, 2, -3, -4, 5, -6).filter(isEven && isNegative))
  }
}