kotlin
class AddingScope {
    var accumulator = 0
    operator fun Wrap.unaryPlus(): AddingScope {
        accumulator += i
        return this@AddingScope
    }
}

operator fun AddingScope.plus(i: Int) = + i.w

inline class Wrap(val i: Int)

fun adding(c: AddingScope.() -> Unit): AddingScope {
    val res = AddingScope()
    res.c()
    return res
}

val Int.w
    get() = Wrap(this)

fun main() {
    val a = adding {
        + 1.w + 2 + 3
        + 4.w + 5 + 6
        + 7.w + 8 + 9
    }.accumulator
    println(a)
}

kotlin
class AddingScope {
    var accumulator = 0
    operator fun Wrap.unaryPlus(): AddingScope {
        accumulator += i
        return this@AddingScope
    }
}

operator fun AddingScope.plus(i: Int) = + i.w

inline class Wrap(val i: Int)

fun adding(c: AddingScope.() -> Unit): AddingScope {
    val res = AddingScope()
    res.c()
    return res
}

val Int.w
    get() = Wrap(this)

fun main() {
    val a = adding {
        + 1.w + 2 + 3
        + 4.w + 5 + 6
        + 7.w + 8 + 9
    }.accumulator
    println(a)
}