Scala and Spark for Big Data Analytics

Exists

Exists checks if a predicate holds for at least one element in the Traversable collection. For example:

def exists(p: ((A, B)) ⇒ Boolean): Boolean  

Using the fat arrow: => is called the right arrow, fat arrow, or rocket and is used for passing parameters by name. That means the expression will be evaluated when a parameter is accessed. It is actually syntactic sugar for a zero parameter function call: x: () => Boolean. Let's see an example using this operator is as follows: package com.chapter4.CollectionAPI object UsingFatArrow { def fliesPerSecond(callback: () => Unit) { while (true) { callback(); Thread sleep 1000 } } def main(args: Array[String]): Unit= { fliesPerSecond(() => println("Time and tide wait for none but fly like arrows ...