LambdaExtension.kt

package readinglist

class Request(val method:String,val query:String,val contentType:String)

class Response(val contents:String,var status:Status){
    fun status(status:Status.() -> Unit){
        //do process
    }
}

class Status(var code:Int,var description:String)


class RouteHandler(val request:Request,val response: Response){
    var executeNext = false
    fun next(){
        executeNext=true
    }
}

fun response(response:Response.() -> Unit){}
fun routeHandler(path:String,f:RouteHandler.() -> Unit):RouteHandler.() -> Unit = f

fun main(args: Array<String>) {
    routeHandler("/index.html"){
        if(request.query!=""){
            //do process
        }
        response { 
            status { 
                code=404
                description="Not Found"
            }
        }
    }
}

LambdaExtensionUsingInvoke.kt

package readinglist
//using invoke to invoke some functionality just by using instance
class Request(val method:String,val query:String,val contentType:String)

class Response(val contents:String,var status:Status){
   
    operator fun invoke(status: Status.() -> Unit) {}
}

class Status(var code:Int,var description:String)


class RouteHandler(val request:Request,val response: Response){
    var executeNext = false
    fun next(){
        executeNext=true
    }
}


fun routeHandler(path:String,f:RouteHandler.() -> Unit):RouteHandler.() -> Unit = f

fun main(args: Array<String>) {
    routeHandler("/index.html"){
        if(request.query!=""){
            //do process
        }
        response {
                code=404
                description="Not Found"
            }
        }
    }
}

Praveen, some great examples. Running main here doesn't return any data. How do you print the response here?