list operations, higher-order methods: filter, partition, takeWhile, dropWhile, and span

gistfile1.scala

object ScalaHackSession {
  //filter all even numbers
  val list = (1 to 10).toList                     //> list  : List[Int] = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
  list.filter(_ % 2 == 0)                         //> res0: List[Int] = List(2, 4, 6, 8, 10)
  //find is like filter but stops after the first true condition
  val result = list.find(element => element > 3 && element % 3 == 0)
                                                  //> result  : Option[Int] = Some(6)
  result match {
    case Some(element) => println(element + ": found")
    case None => println("Not in list")
  }                                               //> 6: found
  //partition where first list fulfills predicate and remainin is in second list
  list.partition(element => element > 3 && element % 3 == 0)
                                                  //> res1: (List[Int], List[Int]) = (List(6, 9),List(1, 2, 3, 4, 5, 7, 8, 10))
  //take all elements while predicate is true
  list.takeWhile(_ < 6)                           //> res2: List[Int] = List(1, 2, 3, 4, 5)
  //drop all elements while predicate is true
  list.dropWhile(_ < 6)                           //> res3: List[Int] = List(6, 7, 8, 9, 10)
  //span a combination of takeWhile and dropWhile
  list.span(_ < 6)                                //> res4: (List[Int], List[Int]) = (List(1, 2, 3, 4, 5),List(6, 7, 8, 9, 10))
}