Looking at language statistics in last rounds I have wondered why so many Java and so extremely low Kotlin coders?

Kotlin, in rude of sense, is modern replace for Java, so...

If you are Java-coder then I am curious why you not change Java to Kotlin?

I don't want to note basic advantages of Kotlin which described everywhere. But it is language with modern syntax, and I think it is cool for cp almost as Python. I have more than one year experience of coding in Kotlin (but not cp!!), and I can describe my feelings as "I will never write even single line again in Java".

Maybe you remembered Kotlin as not so cool language when it was 1.4 but now (1.7 in moment of writing this blog) both syntax and std lib have improvements. For example, instead of readLine()!! now it is readln().

Usage of lambdas in Kotlin is awesome. Just look at this custom comparator:

data class Segment(val l: Int, val r: Int, val id: Int)
...
segments.sortWith(compareBy<Segment> { it.l }
    .thenByDescending { it.r }
    .thenBy { a[it.id] }
)

Or modulo function

val MOD = (1e9 + 7).toInt()
println((-1).mod(MOD)) //1000000006
println(((MOD-1L)*(MOD-2L)).mod(MOD)) //2

Last what I really like is extensions, great for templates/libraries

fun IntRange.firstFalse(pred: (Int) -> Boolean): Int {
    var l = first
    var r = last
    while (l < r) {
        val m = (l + r) / 2
        if (pred(m)) l = m + 1 else r = m
    }
    return r
}

//usage:
val i = (0 .. 2e9.toInt()).firstFalse {
    1L * it * it <= s
}