cf. https://twitter.com/mattn_jp/status/663021972805148673

siden.groovy

@Grab("ninja.siden:siden-core:+")

import ninja.siden.App
import groovy.json.JsonBuilder

Object.metaClass.asJson = {
    def builder = new JsonBuilder(delegate)
    builder.toString()
}

def map = [:]
map['foo'] = 'ハローワールド'
map['bar'] = [1, 2, 3]
map['boo'] = ['hoge' : 'aaa', 'fuga' : [1, 2, ['obj':true]]]

def app = new App()
app.get("/map", { req, res -> map.asJson() })
app.listen()

$ groovy siden.groovy

if you need speed at start.

# require groovyserv
$ groovyclient siden.groovy