Force compilation error with sealed classes

Question

With sealed classes you can use exhaustive when expressions and omit the else clause when the expression returns a result:

sealed c         


        

Answer 1

In inspiration by Voddan's answer, you can build a property called safe you can use:

val Any?.safe get() = Unit

To use:

when (sealedClass) {
    is SealedClass.First -> doSomething()
    is SealedClass.Second -> doSomethingElse()
}.safe

I think it provides a clearer message than just appending .let{} or assigning the result to a value.

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There is an open issue on the Kotlin tracker which considers to support 'sealed whens'.