Maybe I wasn't clear enough. Kotlin checks exhaustivity of when only if it is used as an expression, not as a statement. https://kotlinlang.org/docs/reference

Maybe I wasn't clear enough. Kotlin checks exhaustivity of when only if it is used as an expression, not as a statement. https://kotlinlang.org/docs/reference/control-flow.html#when-expression https://kotlinlang.org/docs/reference/control-flow.html#when... Kotlin doesn't allow destructuring in when: https://discuss.kotlinlang.org/t/destructuring-in-when/2391 https://discuss.kotlinlang.org/t/destructuring-in-when/2391 This is just straight up weak coming from any reasonable ML derived language with real pattern matching.