Lambda syntax and declaration in Kotlin - Mini Project: Build & Apply

Lambda syntax and declaration

📖 Scenario: You are working on a simple Kotlin program that processes a list of numbers. You want to use a lambda function to double each number in the list.

🎯 Goal: Build a Kotlin program that uses a lambda expression to double each number in a list and then prints the doubled numbers.

📋 What You'll Learn

Create a list of integers with exact values

Declare a lambda expression that doubles a number

Use the lambda to transform the list

Print the resulting list

💡 Why This Matters

🌍 Real World

Lambdas are used in Kotlin to write short, reusable pieces of code for tasks like transforming lists, handling events, or processing data streams.

💼 Career

Understanding lambda syntax is essential for Kotlin developers working on Android apps or backend services, as it helps write clean and efficient code.

1

Create the initial list of numbers

Create a list of integers called numbers with these exact values: 1, 2, 3, 4, 5

Kotlin

# Create the list called numbers with values 1, 2, 3, 4, 5
// Your code here

Need a hint?

Use val numbers = listOf(1, 2, 3, 4, 5) to create the list.

2

Declare a lambda expression to double a number

Declare a lambda expression called double that takes an integer n and returns n * 2

Kotlin

val numbers = listOf(1, 2, 3, 4, 5)
// Declare the lambda called double that doubles a number
// Your code here

Need a hint?

Use val double: (Int) -> Int = { n -> n * 2 } to declare the lambda.

3

Use the lambda to transform the list

Create a new list called doubledNumbers by applying the double lambda to each element in numbers using map

Kotlin

val numbers = listOf(1, 2, 3, 4, 5)
val double: (Int) -> Int = { n -> n * 2 }
// Create doubledNumbers by mapping numbers with double
// Your code here

Need a hint?

Use val doubledNumbers = numbers.map(double) to apply the lambda.

4

Print the doubled numbers

Print the doubledNumbers list using println

Kotlin

val numbers = listOf(1, 2, 3, 4, 5)
val double: (Int) -> Int = { n -> n * 2 }
val doubledNumbers = numbers.map(double)
// Print doubledNumbers
// Your code here

Need a hint?

Use println(doubledNumbers) to display the doubled list.