``` private fun whenTest(a: Boolean, b: Boolean) =...

# announcements

[david-wg2]

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

[david-wg2]

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

[david-wg2]

is this a bug?

[edwardwongtl]

Maybe the or cases?

[david-wg2]

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]

just use else -> instead of !a && !b -> 🙂

[david-wg2]

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

[edwardwongtl]

Ah I think I know what’s going on. It asks for a else because there is no bound for when, sth like when (someEnum) { ... }. So the condition branches can be any statement that results in a Boolean. Even though you’re branches covers all possibilities for a and b, there is still infinite possibilities out there that does not involve `a`/`b`.

[david-wg2]

fair point

[edwardwongtl]

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

[david-wg2]

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