You mean this?
val a = 5
when(a) {
   in listOf(1, 2, 3) -> ...

I saw your code link earlier and didn't understand it unfortunately, so I'm unable to help.

General idea of what you want. Can you provide some small synthetic code example of what you want to achieve?

Like, er, nothing. I don't know your domain, so it's better to provide simpler snippers if you ask something on language syntax. At least, this is how I see it.

so i can then dynamically build up a when expression i guess

Oh, so you want to make it a bit more dynamic, but still have breaking semantics and stuff?
You'll probably build a list of pair of functions, first one taking a parameter and returning Boolean, second one just () -> Unit. You can get some visual similarly via custom DSL. I saw an example not so long ago.

I'm sorry, I'm commuting right now, so won't be able to find sample I'm talking about :/

You mean the code? No, it isn't preserved during compilation in text form, so it doesn't exist at the point exception is thrown.
You can probably use class extending () -> Unit with overriden toString,but this may be overengineering for this purpose.

товарищи, я верно понял Котлин

fun readFile(path: String): String? {
        var result: String? = "";
        try {
            val bufferedReader: BufferedReader = Files.newBufferedReader(Paths.get(path), StandardCharsets.UTF_8);
            result = bufferedReader.use { it.readText() };
        } catch (ex: IOException) {
            ex.printStackTrace();
        }
        return result
    }

в данном методе, благодаря знаку ? result теперь может вернуть пустую строку?

? Значит, что это nullable тип и значение может быть null

fun readFile(path: String): String? {
        var result: String? = "";
        try {
            val bufferedReader: BufferedReader = Files.newBufferedReader(Paths.get(path), StandardCharsets.UTF_8);
            result = bufferedReader.use { it.readText() };
        } catch (ex: IOException) {
            ex.printStackTrace();
        }
        return result
    }

Пустую строку (т.е. "") ты можешь вернуть и без nullable типа. С nullable типом ты можешь вернуть именно null. Подробнее тут: https://kotlinlang.org/docs/reference/null-safety.html

Да, спасибо за ответ. Я понял что ? там был лишним

is there a specific class that can hold classes that contain the forEach or iterator member

i tried that but it doesnt work for the String class

in generics, is it possible to specify a vararg with other paramaters without encountering ambuguaty unless named arguments along with *arrayof() is used or if the paramater types differ?
eg
class X<A,B> {


    fun a(X: A, vararg Z: B) = something(X,Z);
    fun a(vararg Z: B) = somethingElse(Z);
}

val x = X<Int,Int>()
x.a(0) // ambigous
x.a(0, 0) // ambigous
x.a(0, *arrayOf(0)) // ambigous
x.a(*arrayOf(0)) // ambigous
x.a(Z = *arrayOf(0)) // OK
x.a(X = 0, Z = *arrayOf(0)) // OK

val x = X<Char,Int>()
x.a('0') // OK, Z is empty
x.a(0) // OK
x.a('0', 0) // OK
x.a('0', *arrayOf(0)) // OK
x.a(*arrayOf(0)) // OK
x.a(Z = *arrayOf(0)) // OK
x.a(X = '0', Z = *arrayOf(0)) // OK

Hello, can someone explain what does CoroutineContext means?

And what does Coroutine scope exist for?

Документацию читали?

Да, но там всё очень расплывчато написано