Scala Programming Projects

Side effects

A function or expression is said to have a side effect when it modifies some state or has some action in the outside world. For instance, printing a string to the console, writing to a file, and modifying a var, are all side effects.

In Scala, all expressions have a type. A statement which performs a side effect is of type Unit. The only value provided by the type Unit is ():

scala> val x = println("hello")hellox: Unit = ()scala> def printName(name: String): Unit = println(name)printName: (name: String)Unitscala> val y = {  var a = 1  a = a+1}y: Unit = ()scala> val z = ()z: Unit = ()

A pure function is a function whose result depends only on its arguments, and that does not have any observable side effect. Scala allows you to mix ...