Scala | Nested Functions

A function definition inside an another function is known as Nested Function. It is not supported by C++, Java, etc. In other languages, we can call a function inside a function, but it’s not a nested function. In Scala, we can define functions inside a function and functions defined inside other functions are called nested or local functions. 
Syntax:

def FunctionName1( parameter1, parameter2, ..) = { 
def FunctionName2() = { 
// code 
} 
}

Single Nested Function
Here is an example of single nested function that takes two numbers as parameters and returns the Maximum and Minimum of them. 
Example

Scala

// Scala program of Single Nested Function
object MaxAndMin
{
    // Main method
    def main(args: Array[String])
    {
        println("Min and Max from 5, 7")
                maxAndMin(5, 7);
    }

    // Function
    def maxAndMin(a: Int, b: Int) = {

       // Nested Function
       def maxValue() = {
          if(a > b)
          {
              println("Max is: " + a)
          }
          else
          {
              println("Max is: " + b)
          }
       }

       // Nested Function
       def minValue() = {
          if (a < b)
          {
              println("Min is: " + a)
          }
          else
          {
              println("Min is: " + b)
          }
       }
       maxValue();
       minValue();
    }
}

Output

Min and Max from 5, 7
Max is: 7
Min is: 5

In above code maxAndMin is a function and maxValue is another inner function returns maximum value between a and b similarly minValue is another inner function which is also nested function this function returns minimum value between a and b. 
Multiple Nested Function
Here is an implementation of multiple nested function. 
Example

Scala

// Scala program of Multiple Nested Function
object MaxAndMin
{
    // Main method
    def main(args: Array[String])
    {
        fun();
    }

    // Function
    def fun() = {

        geeks();

        // First Nested Function
        def geeks() = {
            println("geeks");

            gfg();

            // Second Nested Function
            def gfg() = {
                println("gfg");

                geeksforgeeks();

                // Third Nested Function
                def geeksforgeeks() = {
                    println("geeksforgeeks");
                }
            }
        }
    }
}

Output

geeks
gfg
geeksforgeeks

In above code fun is a function and geeks, gfg, geeksforgeeks are nested functions or local function .