Higher-order function declaration in Kotlin - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a higher-order function that takes a function as a parameter.

Kotlin

fun operateOnNumber(x: Int, operation: (Int) -> Int): Int {
    return operation([1])
}

Drag options to blanks, or click blank then click option'

AInt

Bx

Coperation

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the function name instead of the argument.

Using a variable that is not defined in the function.

The parameter operation is a function that takes an Int and returns an Int. We call it with x inside the function.

2fill in blank

medium

Complete the code to declare a higher-order function that returns a function.

Kotlin

fun makeMultiplier(factor: Int): (Int) -> Int {
    return [1](number: Int) = number * factor
}

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Afun

Bval

Clambda

Dreturn

Attempts:

3 left

💡 Hint

Common Mistakes

Using val instead of fun to declare the function.

Trying to return a lambda without the fun keyword.

The function makeMultiplier returns another function. Using fun declares an anonymous function to return.

3fill in blank

hard

Fix the error in the higher-order function declaration that takes two functions as parameters.

Kotlin

fun combineOperations(x: Int, op1: (Int) -> Int, op2: (Int) -> Int): Int {
    return op2(op1([1]))
}

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Aop1

Bop2

Cx

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the function op1 itself instead of its argument.

Using an undefined variable instead of x.

The function combineOperations applies op1 to x, then op2 to the result. So x must be passed to op1.

4fill in blank

hard

Fill both blanks to declare a higher-order function that takes a function and returns a function.

Kotlin

fun transformFunction(f: (Int) -> Int): (Int) -> Int {
    return [1](x: Int) = f(x) + [2]
}

Drag options to blanks, or click blank then click option'

Afun

Bx

C1

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Using val instead of fun.

Forgetting to add 1 to the result.

We declare an anonymous function with fun that takes x and returns f(x) + 1. The 1 is added to the result.

5fill in blank

hard

Fill all three blanks to declare a higher-order function that takes a function and returns a function that applies it twice.

Kotlin

fun twice(f: (Int) -> Int): (Int) -> Int {
    return [1](x: Int) = f(f([2])) + [3]
}

Drag options to blanks, or click blank then click option'

Afun

Bx

C0

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Using val instead of fun.

Forgetting to pass x to f.

Adding a number other than 0.

The function twice returns an anonymous function declared with fun. It applies f twice to x and adds 0 (no change).