enum class DateAttribute : UpcomingPaymentAttribute

data class DateKey(val startDate: LocalDate, val granularity: DateAttribute)

...
            // it is UpcomingPaymentAttribute
            when (it) {
                DateAttribute.DAY -> DateKey(LocalDate.now(), it) // here compiler complains that it is UpcomingPaymentAttribute, not DateAttribute

it

var

Type mismatch: inferred type is UpcomingPaymentAttribute but DateAttribute was expected

it

DateAttribute

it

UpcomingPaymentAttribute

when

it

DateAttribute.DAY

it

DateAttribute

is DateAttribute

when

it == DateAttribute.DAY

it is DateAttribute

===

interface Parent

enum class Child : Parent {
    THREE, FOUR
}

fun doIt(param: Child) {
    println (param)
}

val a: Parent = Child.THREE

when (a) {
    Child.THREE -> doIt(a)
    Child.FOUR -> {}
}

when {
    a is Child && a == Child.THREE -> doIt(a)

when (a) {
    Child.THREE -> doIt(a as Child)

equals

you can override equals

===

when

when (it) {
    is YourEnum -> when (it) {
        YourEnum.FirstElement -> …
        YourEnum.SecondElement -> …
    }
    else -> …
}

when

switch

is

equals

interface Parent

object O : Parent {
    override fun equals(other: Any?): Boolean {
        return true
    }
}

enum class Child : Parent {
    ONE, TWO;
}

var o: Parent = O

fun main() {
    println(o.equals(Child.ONE)) // true
    println(o == Child.ONE)  // false!
    val n = when (o) {
        Child.ONE -> 1
        Child.TWO -> 2
        O -> 3
        else -> 4
    }
    println(n)  // 3, not 1
}

==

equals