Immutability | High performance with idiomatic Kotlin

Immutability.kt

interface ValueHolder<V> {
    val value: V
}
class IntHolder : ValueHolder<Int> {
    override val value: Int
        get() = Random().nextInt()
}
fun main() {
    val sample = IntHolder()
    println(sample.value) //260078462
    println(sample.value) //1657381068
}

// immutability by default
data class ImmutableKey(val name: String? = null)