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Scala Functions and Methods

A Scala function is a block of executable code that returns a value or a function by itself. 

//add function in scala which takes two parameters of type Int and returns Int
def add(value1: Int ,value2: Int ): Int = {
    val sum = value1 +value2;
    sum
}

We can write a concise form of the above code using Scala. 


def add(value1: Int ,value2: Int) = value1 + value2


Methods in Scala

Methods in Scala is a function that is a member of an object. A method has access to all the fields of the object to which it belongs.

Local Functions

Local functions are functions that are defined inside the function. This function will have access to variables defined within that specific function.

Higher-order Functions

A Higher-order function is a function that takes another function as input.

def encode(n: Int, f: (Int) => Long): Long = {
val x = n * 10;
f(x)
}


//Sum() returns a function that takes two Integer and Returns an Integer
  def sum(f: Int => Int):(Int, Int) => Int ={
    def sumf(a: Int ,b:Int): Int ={
      a+b
    }
    sumf
  }

//Same as Above .
//Its type is (Int => Int) => (Int ,Int) => Int
  def sum(f:Int => Int)(a:Int ,b:Int):Int = a+b

//Called like this
sum(x: Int) => x * x * x) //Anonmous Function which does not have a name

sum(x => x * x * x)    //Same anonymous function with type inferred


def cube(x: Int) = x * x * x
sum (x => x * x * x)(1, 10) //Sum of cubes from 1 to 10

sum(cube) (1 ,10) //Same as above

Function Literal

A function literal is an unnamed or anonymous function in Scala code. It can be used in an application just like a string literal. It can be passed as an input to a higher-order method or function. Furthermore, it can also be assigned to a variable. 

(x: Int) => {
              x+100
             }

We can use a single line for a single statement.

 (x: Int) => x + 200
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