What are views for collections and when would you want to use them?

Question

In Scala, for many (all?) types of collections you can create views.

What exactly is a view and for which purposes are views useful?

Answer 1

One use case is when you need to collect first result of elements transformation:

    case class Transform(n: Int) { println("Transform "+n)}
    val list = List(1,2,3,4,5)
    list.view.map(v => Transform(v)).collectFirst{case Transform(3) => println("found")}

Prints:

Transform 1
Transform 2
Transform 3
found

While:

    list.map(v => Transform(v)).collectFirst{case Transform(3) => println("found")}

Prints:

Transform 1
Transform 2
Transform 3
Transform 4
Transform 5
found