@Composable
fun App(appData: AppData) {
    val derivedData = compute(appData)
    Header()
    if (appData.isOwner) {
        EditButton()
    }
    Body {
        for (item in derivedData.items) {
            Item(item)
        }
    }
}

class Input : View() { /* ... */}

class ValidatedInput : Input() { /* ... */}

class DateInput : ValidatedInput() { /* ... */}

class DateRangeInput : ???() { /* ... */}

@Composable
fun <T> Input(value: T, onChange: (T) -> Unit) {
    /* ... */
}

@Composable
fun ValidatedInput(value: T, onChange: (T) -> Unit, isValid: Boolean) {
    InputDecoration(color = if(isValid) blue else red) {
        Input(value, onChange)
    }
}

@Composable
fun DateInput(value: DateTime, onChange: (DateTime) -> Unit) {
    ValidatedInput(
        value,
        onChange = { ... onChange(...) },
        isValid = isValidDate(value)
    )
}

@Composable
fun DateRangeInput(value: DateRange, onChange: (DateRange) -> Unit) {
    DateInput(value = value.start, ...)
    DateInput(value = value.end, ...)
}

fun onCreate() {
    var count = 0
    
    button.setOnClickListener {
        count++
        button.text = "Count: $count"
    }
}

@Composable
fun Messages(liveMessages: LiveData<MessageData>) {
    val messages = +observe(liveMessages)
    for (message in messages) {
    	Message(message)
    }
}

@Composable
fun Counter() {
    val count = state { 0 }

    Button(onClick = { count.value++ }) {
        Text("Count: ${count.value}")
    }
}

fun Example(a: () -> Unit, b: @Composable() () -> Unit) {
    a() // Permitido
    b() // NO permitido
}

@Composable
fun Example(a: () -> Unit, b: @Composable() () -> Unit) {
    a() // Permitido
    b() // Permitido
}