JavaScript with S Expression powered by tagged template string.
For fun.
Node 4.x or babeljs.
$ npm install s-exp
const s = require('s-exp')
const assert = require('assert')
s`
(def a 1)
(def b 2)
(.equal ${assert} (+ a b) 3)
(def sleep (fn [time]
(new Promise (fn [resolve]
(setTimeout resolve time)))))
`