Implementing Iterable

Question

How to implement Scala equivalent to Java Iterable<T> and C# IEnumerable<T>? Basically, I want my collection to be mappable, filterable etc. What traits should the collection class extend and are there easy ways (something like yield return and yield break in C#) to create enumerator?

Answer 1

Implement the Iterable trait. All that is required is the iterator method. All the other methods (map, filter, etc) come for free.

class MyIterable[T](xs: Vector[T]) extends Iterable[T] { 
  override def iterator = xs.iterator 
}

val a = new MyIterable(Vector(1,2,3))
a.map(_+1) // res0: Iterable[Int] = List(2, 3, 4)
a.filter(_%2==1) // res1: Iterable[Int] = List(1, 3)