<@U589QURRQ> can I consider this syntax `-&gt;` in lamdas as return?

# getting-started

[Ayden]

@diesieben07 can I consider this syntax -> in lamdas as return?

[diesieben07]

Not quite. The return value of a lambda is usually it's last expression: https://kotlinlang.org/docs/reference/lambdas.html#returning-a-value-from-a-lambda-expression

[Ayden]

What does the @lit use for?

[Ayden]

There is another annotation like @filter

[edwardwongtl]

Usually return@filter, making a return to another scope

[edwardwongtl]

a simple return will only return from the current function scope.

[Ayden]

@edwardwongtl where can I find those annotation documentation?

[edwardwongtl]

That’s not quite a annotation, search for Non-local return

[Ayden]

@edwardwongtl non-local return is useful if you still want to process something after return is it?

[edwardwongtl]

It is useful when you are nesting too much lambdas

[Ayden]

I have an issue here.
How come these two produce different outcomes?

fun foo() {
    run loop@{
        listOf(1, 2, 3, 4, 5).forEach {
            if (it == 3) return@loop // non-local return from the lambda passed to run
            print(it)
        }
    }
    print(" done with nested loop")
}

12 done with nested loop

fun foo() {
    run {
        listOf(1, 2, 3, 4, 5).forEach {
            if (it == 3) return@forEach
            // non-local return from the lambda passed to run
            print(it)
        }
    }
    print(" done with nested loop")
}

1245 done with nested loop

[Ayden]

I read the previous example, actually this two can produce the same value.

[edwardwongtl]

return@forEach actually work as continue

[Ayden]

@edwardwongtl
This line of code is similar like continue or return@forEach right?

fun foo() {
    listOf(1, 2, 3, 4, 5).forEach lit@{
        if (it == 3) return@lit // local return to the caller of the lambda, i.e. the forEach loop
        print(it)
    }
    print(" done with explicit label")
}

fun main(args: Array<String>) {
    foo()
}

[Ayden]

fun foo() {
    run loop@{
        listOf(1, 2, 3, 4, 5).forEach {
            if (it == 3) return@loop // non-local return from the lambda passed to run
            print(it)
        }
    } <- Here is the end of the local scope right?
    print(" done with nested loop")
}

[Ayden]

This is the last example of the non-local return.

[Ayden]

The reason why the result terminal at 12 done with nested loop is because the end of the local scope is after the close bracket of the run.

[Ayden]

Am I right?

[Shawn]

You might want the docs for labels and using return with them https://kotlinlang.org/docs/reference/returns.html