How to Return from Lambda in Kotlin: Simple Guide

In Kotlin, to return from a lambda, use an implicit return by placing the expression as the last line or use a labeled return with return@label to exit the lambda explicitly without returning from the enclosing function.

Syntax

In Kotlin, lambdas can return values implicitly by having the last expression as the return value. To return explicitly from a lambda without exiting the outer function, use a labeled return with return@label.

• Implicit return: The last expression in the lambda is returned automatically.
• Labeled return: Use return@label to return from the lambda itself.

kotlin

val numbers = listOf(1, 2, 3, 4, 5)
numbers.forEach label@{
    if (it == 3) return@label  // returns from lambda, continues forEach
    println(it)
}

Output

1
2
4
5

Example

This example shows how to return from a lambda inside a forEach loop. Using return@forEach skips the current iteration without exiting the whole function.

kotlin

fun main() {
    val numbers = listOf(1, 2, 3, 4, 5)
    numbers.forEach {
        if (it == 3) return@forEach  // skip printing 3
        println(it)
    }
    println("Done")
}

Output

1
2
4
5
Done

Common Pitfalls

A common mistake is using return inside a lambda without a label, which causes the enclosing function to return, not just the lambda. This can lead to unexpected behavior.

Wrong way (exits whole function):

kotlin

fun main() {
    val numbers = listOf(1, 2, 3)
    numbers.forEach {
        if (it == 2) return  // returns from main(), stops all processing
        println(it)
    }
    println("This will not print")
}

Output

1

Right way (returns only from lambda):

kotlin

fun main() {
    val numbers = listOf(1, 2, 3)
    numbers.forEach {
        if (it == 2) return@forEach  // returns from lambda only
        println(it)
    }
    println("This will print")
}

Output

1
3
This will print

Key Takeaways

Use return@label to return from a lambda without exiting the outer function.

The last expression in a lambda is returned implicitly if no explicit return is used.

A plain return inside a lambda returns from the enclosing function, not just the lambda.

Label your lambdas or use standard labels like return@forEach to control flow clearly.

Understanding return behavior in lambdas helps avoid unexpected program exits.