Why lambdas enable functional style in Kotlin - See It in Action

Why lambdas enable functional style

📖 Scenario: Imagine you are organizing a list of tasks and want to quickly filter and transform them without writing long, repetitive code. Lambdas help you do this in a neat and functional way.

🎯 Goal: You will create a list of tasks, set a filter condition using a lambda, apply a transformation with another lambda, and finally print the results. This shows how lambdas enable a functional style in Kotlin.

📋 What You'll Learn

Create a list of tasks as strings

Create a lambda to filter tasks containing the word 'code'

Create a lambda to transform tasks to uppercase

Use the lambdas with Kotlin's collection functions

Print the final transformed list

💡 Why This Matters

🌍 Real World

Lambdas let you write clean and reusable code for filtering and transforming data, common in apps and backend services.

💼 Career

Understanding lambdas and functional style is important for Kotlin developers to write modern, efficient, and maintainable code.

1

Create a list of tasks

Create a list called tasks with these exact strings: "write code", "review code", "test app", "deploy app"

Kotlin

# Create the list called tasks with the given strings
# Your code here

Need a hint?

Use listOf to create the list with the exact strings.

2

Create a filter lambda

Create a lambda called filterCodeTasks that takes a String and returns true if it contains the word "code"

Kotlin

val tasks = listOf("write code", "review code", "test app", "deploy app")
# Create the lambda filterCodeTasks to check if a task contains "code"
# Your code here

Need a hint?

Use the lambda syntax with { task -> task.contains("code") }.

3

Create a transform lambda

Create a lambda called toUpperCase that takes a String and returns the uppercase version of it

Kotlin

val tasks = listOf("write code", "review code", "test app", "deploy app")
val filterCodeTasks: (String) -> Boolean = { task -> task.contains("code") }
# Create the lambda toUpperCase to convert a string to uppercase
# Your code here

Need a hint?

Use uppercase() inside the lambda to convert the string.

4

Filter, transform, and print tasks

Use tasks.filter(filterCodeTasks) to get tasks containing "code", then use map(toUpperCase) to convert them to uppercase, and finally print the resulting list with println

Kotlin

val tasks = listOf("write code", "review code", "test app", "deploy app")
val filterCodeTasks: (String) -> Boolean = { task -> task.contains("code") }
val toUpperCase: (String) -> String = { task -> task.uppercase() }
# Filter tasks with filterCodeTasks, map them with toUpperCase, then print the result
# Your code here

Need a hint?

Chain filter and map with the lambdas, then print the list.