import scala.collection.generic.CanBuildFrom
object collections {
val arr = Array("a", "b")
val aa = arr ++ arr
List(1, 2, 3) map (x => 2)
val s = Set(1, 2, 3)
val ss = s map (_ + 1)
val cbf: CanBuildFrom[List, Int, List[Int]] = scala.collection.immutable.List.canBuildFrom
val nil = Nil
val ints1 = 1 :: Nil
val ints2 = 1 :: 2 :: Nil
val ints3: List[Int] = ints2
val f = (x: Int) => x + 1
val ints4: List[Int] = List(1, 2, 3, 5)
val ys = ints3 map (x => x + 1)
val zs = ys filter (y => y != 0)
val chrs = "abc"
def do2(x: Int, y: Char) = ()
chrs foreach println
(ints2, chrs).zipped foreach do2
val xs = List(List(1), List(2), List(3)).iterator
println(xs.flatten)
}