Head First Kotlin

Chapter 11. lambdas and higher-order functions: Treating Code Like Data

Want to write code that’s even more powerful and flexible?

If so, then you need lambdas. A lambda—or lambda expression—is a block of code that you can pass around just like an object. Here, you’ll discover how to define a lambda , assign it to a variable , and then execute its code . You’ll learn about function types, and how these can help you write higher-order functions that use lambdas for their parameter or return values. And along the way, you’ll find out how a little syntactic sugar can make your coding life sweeter .: Treating Code Like Data

Introducing lambdas

Throughout this book, you’ve seen how to use Kotlin’s built-in functions, and create your own. But even though we’ve covered a lot of ground, we’re still just scratching the surface. Kotlin has a pile of functions that are even more powerful than the ones you’ve already encountered, but in order to use them, there’s one more thing you need to learn: how to create and use lambda expressions.

A lambda expression, or lambda, is a type of object that holds a block of code. You can assign a lambda to a variable, just as you can any other sort of object, or pass a lambda to a function which can then execute the code it holds. This means that you can use lambdas to pass specific behavior to a more generalized function.

Using lambdas in this way ...