How could I implement an "async" (for Deferred<...

# coroutines

[Alowaniak]

How could I implement an "async" (for Deferred<Boolean>) or/and?
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[diesieben07]

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

[Alowaniak]

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

[diesieben07]

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

[diesieben07]

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

[jw]

you need a select

[groostav]

@diesieben07 to elaborate on what jake said:

https://gist.github.com/Groostav/ac3f4090199153b2db94fa2016b20852

[groostav]

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]

If you consider val a: Boolean val b: Boolean a || b, a is evaluated first and THEN b, which the results happen to be available already so it can immediately evaluate. It seems inconsistent that a Deferred variant would potentially evaluate b first instead of awaiting the value of a