I am correct in understanding how anonymous functions works in Kotlin?

I would consider what happens if this anonymous function is in-pure - it access something from outside function

val shift = 2

val add2 = fun (x: Int, y: Int): Int {
    return x + y + shift
}

As I recall this is how variables val/var variables captured by lambda are stored:

val

- value is copied to anonymous class

var

- value is stored in anonymous class as a reference to class that holds value

That's nice. Haven't thought about it. Thanks for this

BTW you may just compile Kotlin class and then decompile it using Java decompiler http://jd.benow.ca/

That doesn't show the result what I am expecting. Instead of the real anonymous class, it shows something like add2 = (Function2) add2.1.INSTANCE

Hard to say. Either Kotlin compiler is optimised or decompiled code is somehow messed up. Can’t help more here.