Have you used sealed classes in your projects?

Yes, in Kotlin projects for Android, I used sealed classes to model limited hierarchies of states or events. Sealed classes allow defining a set of subclasses known at compile time, which simplifies handling through when without needing to write an else branch.

Example of using a sealed class to describe loading states:

sealed class LoadState {
    object Loading : LoadState()
    data class Success(val data: List<String>) : LoadState()
    data class Error(val error: Throwable) : LoadState()
}

fun handleState(state: LoadState) {
    when(state) {
        is LoadState.Loading -> println("Loading...")
        is LoadState.Success -> println("Data received: ${state.data}")
        is LoadState.Error -> println("Error: ${state.error.message}")
    }
}

This helps make the code safer and more readable, especially when working with UI states or operation results.