collectionView.scala

scala> List(1,2,3,4,5) map {x => println("x"); x} map {y => println("y"); y}
x
x
x
x
x
y
y
y
y
y
res0: List[Int] = List(1, 2, 3, 4, 5)

scala> val a = List(1,2,3,4,5).view map {x => println("x"); x} map {y => println("y"); y} 
a: scala.collection.SeqView[Int,Seq[_]] = SeqViewMM(...)

scala> a(3)
x
y
res1: Int = 4