Why lambdas enable functional style in Kotlin - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a lambda that adds two numbers.

Kotlin

val sum = { a: Int, b: Int -> a [1] b }

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

A*

B-

C+

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Using subtraction or multiplication instead of addition.

Forgetting the operator inside the lambda.

The lambda uses the plus operator + to add two numbers.

2fill in blank

medium

Complete the code to filter a list using a lambda that keeps even numbers.

Kotlin

val evens = numbers.filter { [1] % 2 == 0 }

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Ait

Bx

Cnum

Dn

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name without declaring it.

Not using the implicit it parameter.

The implicit lambda parameter it represents each element in the list.

3fill in blank

hard

Fix the error in the lambda that multiplies each number by 2.

Kotlin

val doubled = numbers.map { [1] * 2 }

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

Anumber

Bit

Cnum

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using variable names not declared in the lambda.

Forgetting to use it for single-parameter lambdas.

The lambda uses the implicit parameter it to refer to each element.

4fill in blank

hard

Fill both blanks to create a lambda that filters words longer than 3 letters.

Kotlin

val longWords = words.filter { word -> word.[1] > [2] }

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

Alength

Bsize

C3

D4

Attempts:

3 left

💡 Hint

Common Mistakes

Using size which is not a string property.

Comparing to 4 instead of 3.

The property length gives the number of letters in a word, and we compare it to 3.

5fill in blank

hard

Fill all three blanks to create a map of word lengths for words longer than 4 letters.

Kotlin

val wordLengths = words.filter { [1] -> [1].[2] > [3] }.associateWith { it.length }

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

Aw

Blength

C4

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using size which is not a string property.

Using inconsistent variable names.

Use w as the lambda parameter, length to get string length, and compare to 4.