Kotlin Brain Teasers

Puzzle 9

That’s Not What I Ordered

src/commonMain/kotlin/com/example/puzzles/types/erasure/FilterInstances.kt

sealed class MenuItem(val name: String) {
  override fun toString() = name
}

class Food(name: String): MenuItem(name)
class Drink(name: String): MenuItem(name)

fun main() {
  val wine: Set<Drink> = setOf(Drink("Merlot"), Drink("Chardonnay"))
  val beer: Set<Drink> = setOf(Drink("IPA"), Drink("Lager"))
  val food: Set<Food> = setOf(Food("Pizza"), Food("Pasta"))

  val menu: List<Set<MenuItem>> = listOf(food, wine, beer)

  println("Food: " + menu.filterIsInstance<Set<Food>>().flatten())
  println("Drinks: " + menu.filterIsInstance<Set<Drink>>().flatten())
}

Guess the Output
	Try to ...