``` private fun whenTest a Boolean b Boolean = when a amp amp b gt a amp amp b gt a amp amp b gt a amp amp b gt ```

just use `else gt ` instead of ` a amp amp b gt ` slightly smiling face

``` private fun whenTest a Boolean b Boolean = when a amp am kotlinlang #announcements

09/11/2018, 8:52 AM

private fun whenTest(a: Boolean, b: Boolean) = when {
    a && b -> ""
    !a && b -> ""
    a && !b -> ""
    !a && !b -> ""
}

i'm being told this when expression isn't exhaustive, and that it needs an

else

is this a bug?

edwardwongtl

09/11/2018, 8:59 AM

or

09/11/2018, 9:02 AM

this is an exhaustive truth table, no matter what other ways of checking the variables you introduce, it will be covered by one of these checks

Pavlo Liapota

09/11/2018, 9:06 AM

else ->

!a && !b ->

09/11/2018, 9:07 AM

i know i can do that, but the compiler is lying

edwardwongtl

09/11/2018, 9:10 AM

Ah I think I know what’s going on. It asks for a

else

because there is no bound for

when

when (someEnum) { ... }

. So the condition branches can be any statement that results in a

Boolean

. Even though you’re branches covers all possibilities for

, there is still infinite possibilities out there that does not involve `a`/`b`.

09/11/2018, 9:12 AM

edwardwongtl

09/11/2018, 9:13 AM

Technically it is not a bug, but maybe some room for improvement.

09/11/2018, 10:57 AM

i created an issue for it (a feature request), but it turns out it's already registered as a bug: https://youtrack.jetbrains.net/issue/KT-20943