Kotlin Academy · Lesson

let and run

Operate on objects.

What Are Scope Functions?

Kotlin offers five scope functions: let, run, with, apply, and also. They let you execute a block of code on an object inside a temporary scope.

You refer to the object as it or this.
The block returns either the object itself or the lambda result.

In this lesson we focus on let and run.

The let Function

let executes a block where the object is available as it, and returns the lambda result.

It is great for running code only when a value is non-null, and for transforming a value into something else.

fun main() {
    val name = "Alice"
    val length = name.let {
        println("Name is $it")
        it.length
    }
    println("Length: $length")
}

All lessons in this course

let and run
apply and also
with
Choosing the Right One

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