Variance.kt

// Why do we need variance

// Invariant class List, just like in Java
class List<T> { /* normal list */ }

fun printContents(list: List<Any>) {
    for (item in list) {
        println(item)
    }
}

fun test() {
    val list: List<String> = listOf("a", "b")
    
    printContents(list) // ERROR: List<String> is not a subtype of List<Any>
}

Ok. Andrey, thank you very much for participation and for your time. It was very interesting and informative discussion. I hope we will have a chance to continue it later.

I'm following your project with interest. Albeit we have different points of view in some controversial problems, I must admit JetBrains making the best products in its market. And there is no doubt, Kotlin is one of them.

P.S. I'm going to add you on my Skype contact list, so we will be in touch.

Just for the record. On the matter of variance in Java (which is called use-site variance): https://prezi.com/lnw_oiv1gs-j/java-8-vs-kotlin/