Answer code for XTANCE

Scripting.kt

import javax.script.ScriptEngine
import javax.script.ScriptEngineManager
import kotlin.reflect.KProperty

fun main(args: Array<String>) {
    with(ScriptEngineManager().getEngineByExtension("kts")) {
//        val x by value { 3 }
//        println(x)

//        val x = value("x", 3)
//        println(x)
        eval("val x = 3")
        val res2 = eval("\"hello \$x \${x+3}\"")
        println(res2)
        println(eval(readLine()))
    }
}

//doesn't work if you doesn't use as program variable before using in script engine
fun <T: Any> ScriptEngine.value(init: () -> T): Delegate<T> {
    return object: Delegate<T> {
        val value = { paramName: String ->
            val i = init()
            this@value.eval("val $paramName = $i")
            i
        }
        lateinit var valueInit: T
        override operator fun getValue(thisRef: Any?, property: KProperty<*>): T {
            if (!::valueInit.isInitialized) {
                valueInit = value(property.name)
            }
            return valueInit
        }
    }
}

//variable name duplication
fun <T: Any> ScriptEngine.value(name: String, value: T): T {
    eval("val $name = $value")
    return value
}

interface Delegate<T: Any> {
    operator fun getValue(thisRef: Any?, property: KProperty<*>): T
}