``` val a Deferred lt Boolean gt = TODO val b Deferred lt Boolean gt = TODO val result = async a await || b await ```

``` val a Deferred lt Boolean gt = TODO val b Deferred lt Bo kotlinlang #coroutines

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Title

diesieben07

08/06/2018, 10:00 PM

val a: Deferred<Boolean> = TODO()
val b: Deferred<Boolean> = TODO()
val result = async {
    a.await() || b.await()
}

Alowaniak

08/06/2018, 10:07 PM

won't this wait for a first, then b though? Instead of short circuiting when b returns true before a?

diesieben07

08/06/2018, 10:12 PM

oh, that is true. you would have to do two async's then

Actually, that is not true. Not quite sure how you would do it with short-circuit tbh

08/06/2018, 10:40 PM

you need a

select

groostav

08/07/2018, 1:46 AM

@diesieben07 to elaborate on what jake said: https://gist.github.com/Groostav/ac3f4090199153b2db94fa2016b20852

I think one of the problems with short circuiting as such is that

Deferreds

are eager by default, in other words, when you write

async

, we dont create a lazy coroutine by default. In other words, by expressing

right

as a Deferred, its already running, so you've already lost the point of short-circuiting typically. If you chose to express it as a

suspend () -> Boolean

though...

bdawg.io

08/07/2018, 5:41 PM

If you consider

val a: Boolean

val b: Boolean

a || b

is evaluated first and THEN

, which the results happen to be available already so it can immediately evaluate. It seems inconsistent that a

Deferred

variant would potentially evaluate

first instead of awaiting the value of

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