CollectionsFilter.scala

val evens = List(2,4,6)
val odds = List(1,3,5)
val a = "foo bar baz"
val foo = "foo"
val bar = "bar"
val names = List("Al","Chistina","Kim")
val firstTen = (1 to 10).toList
val fiveToFifteen = (5 to 15).toList

//Filter
a.distinct                // "fo barz"
a.drop(4)                 // "bar baz"
a.dropRight(2)            // "foo bar b"
a.dropWhile(_ != ' ')     // " bar baz"

a.filter(_ != 'a')        // "foo br bz"
a.filterNot(_ != 'a')     // "aa"
a.filterNot(_ == 'a')     // "foo br bz"
firstTen.find(_ > 4)      // Some(5)

a.head                    // f
a.headOption              // Some(f)

"foo bar".init            // "foo ba"

List(1,2,3).last          // 3
List(1,2,3).lastOption    // Some(3)

a.slice(0,5)              // foo b
a.slice(2,9)              // o bar b

a.tail                    // oo bar baz
a.take(3)                 // foo
a.takeRight(3)            // baz
a.takeWhile(_ != 'r')     // foo ba
Seq(1,1,2,2,3,3).toSet    // Set(1, 2, 3)

firstTen.withFilter(_ > 5)              // scala.collection.generic.FilterMonadic[Int,List[Int]]
firstTen.withFilter(_ > 5).map(_ * 1)   // List[Int] = List(6, 7, 8, 9, 10)