Collections

Scala provides both mutable and immutable collections. Immutable collections never change. By default, we use immutable collections.

object Predef {
  type Map[A, +B] = immutable.Map[A, B]
}

Immutable collections

Immutable collections are found in scala.collections.immutable package. Here is the tree.

We mostly use immutable collections in practice.

immutable-collections-tree

mutable-collections-tree