Kotlin Tail Recursion and Higher Order Functions

FAQ

Q. What is tailrec?
A. tailrec keyword is used for tail recursion in kotlin.

Q. What are higher order functions?
A. higher order functions are the functions that can return a function and can accept a function as argument.

Q. What is the use of higher order functions?
A. Higher order functions are used a lot in functional programming, they can help generate new functions as per requirements.

Q. What is it keyword?
A. When using a lambda function we can simply use it we have only a single value.

MCQ

Q. Which of the following declaration is syntactically correct?
a) fun myFun(num1: Int): (Int) -> Int = { num2 -> num1 * num2}
b) fun myFun(num1: Int): (Int) : Int = { num2 -> num1 * num2}
c) fun myFun(num1: Int): (Int) -> Int : { num2 -> num1 * num2}
d) fun myFun(num1: Int): (Int) = Int  -> { num2 -> num1 * num2}

A. a) fun myFun(num1: Int): (Int) -> Int = { num2 -> num1 * num2}

Q. What type of function is mult3?
    fun main() {
        val mult3 = makeMathFunc(3)
        println("5 * 3 = ${mult3(5)}")   
    }

    fun makeMathFunc(num1: Int): (Int) -> Int = { num2 -> num1 * num2}
a) higher order function taking function as input
b) lambda function
c) higher order function returning a function
d) a normal function

A. d) a normal function

Q. Where is the function myFunc doing?
    fun main() {
        val multiply2 = {num1: Int -> num1 * 2}
        val numList2 = arrayOf(1,2,3,4,5)
        mathOnList(numList2, multiply2)  
    }

    fun mathOnList(numList: Array<Int>, myFunc: (num: Int) -> Int){
        for(num in numList){
            println("MathOnList : ${myFunc(num)}")
        }
    }
a) multiply the passed number num by num1
b) multiply the passed number num by 2

A. b) multiply the passed number num by 2

Q. What is tail recursion?
a) starts calculating the values after reaching the base case
b) reaches the base case while calculating and storing the values.

A. b) reaches the base case while calculating and storing the values.