Fluent Kotlin DSL for building JSON trees

JSObj.kt

@DslMarker
annotation class JSBuilderDsl

@DslMarker
annotation class JSSetterDsl

data class JSObj(val map: MutableMap<String, Any?> = linkedMapOf()) : MutableMap<String, Any?> by map {

    object Arr {
        @JSBuilderDsl
        operator fun get(vararg items: Any?) = items
    }

    @JSBuilderDsl
    val arr = Arr

    /**
     * set primitive
     */
    infix operator fun String.rem(value: Any?) = this `⁚` value //two escaped dots if inlined

    @JSSetterDsl
    /**
     * set primitive
     */
    infix fun String.`⁚`(t: Any?) {
        map[this] = t
    }

    /**
     * set object
     */
    @JSSetterDsl
    operator fun String.invoke(block: JSObj.() -> Unit) {
        map[this] = JSObj().apply(block)
    }

    /**
     * set array
     */
    @JSSetterDsl
    operator fun String.get(vararg items: Any?) {
        map[this] = items
    }
}

typealias JSArr<T> = Array<T>

/**
 * build array
 */
@JSBuilderDsl
fun <T> arr(vararg items: T): JSArr<out T> = items
/**
 * build object
 */
@JSBuilderDsl
fun obj(block: JSObj.() -> Unit): JSObj = JSObj().apply(block)

val `{}` get() = JSObj()

fun main() {

    val myJsObject  = obj {
        "boolean" % true
        "number" % 1
        "string" % "str"
        "null" % null
        "array"[
                1,
                "str",
                null,
                `{}`,
                arr[1, "2", null, 3]
        ]
        "object" {
            "boolean" % true
            "number" % 1
            "string" % "str"
            "null" `⁚` null
            "array"[1, "str", null]
        }
    }

    System.err.println(myJsObject)//put breakpoint here.
}