Scala and Spark for Big Data Analytics

Nested functions

Why will you require a nested functions support in your programming language? Most of the time, we want to maintain our methods to be a few lines and avoid overly large functions. A typical solution for this in Java would be to define all these small functions on a class level, but any other method could easily refer and access them even though they are helper methods. The situation is different in Scala, so you can use define functions inside each other, and this way, prevent any external access to these functions:

def sum(vector: List[Int]): Int = {  // Nested helper method (won't be accessed from outside this function  def helper(acc: Int, remaining: List[Int]): Int = remaining match {    case Nil => acc case _ => helper(acc ...