~There is no `return`ing from lambdas~

# announcements

[diesieben07]

There is no `return`ing from lambdas

[spand]

Sure you can. You just need to name it

[diesieben07]

val x: (Int) -> Int = {
    // cannot return here
}

[rook]

yes, you can

[rook]

You can most certainly return from lambdas

int foo = 4
foo.let{
  if(it != 4) {
    return@let
  }
  else {
    Timber.d("foo")
  }
}

is perfectly functioning code

[diesieben07]

You are returning from let, that is a normal function. You are not returning from the lambda.

[spand]

https://kotlinlang.org/docs/reference/returns.html#return-at-labels

[rook]

You are technically correct, which is the best kind

[diesieben07]

Well... actually I am not correct as @spand just showed. I didn't know about labeling lambdas. Sorry. 🙈

[hho]

AFAIK you are actually both correct – return won't work when you assign the lambda to a variable...

[rook]

I’ve learned an important lesson today. Lambdas are hard, and I know less than Jon Snow

[diesieben07]

@hho Yes, they do:

val x: (Int) -> Int = lit@{
    return@lit 13
}

[diesieben07]

Once again, the return@let thing shown above does not "return from the lambda", it returns early from let (which is an inline function).

[hho]

Yeah, but isn't that the useful case? That's at least what I meant – you can't return from, say, a foreach with a lambda stored in a val.

[diesieben07]

You can return from the lambda just fine. What you cannot do is return from the function calling forEach.

[hho]

You also can't return from forEach…

[hho]

(which does work, if you don't assign it to a variable)

[diesieben07]

Yes, true.