json from clojure

core.clj

(ns clojure-json.core
  (:require [cheshire.core]))

(defn my-json
  [numbers-to-take numbers-to-map]
  {:time           (new java.util.Date)
   :topic          "Generating json from clojure"
   :numbersToTake  numbers-to-take
   :letsNestIt     {:someNumbers (take numbers-to-take (repeatedly rand))}
   :numbersDoubled (map (partial * 2) numbers-to-map)})

(defn -main
  "Let's generate some json"
  []
  (->>
       (my-json 2 [2 3 4])
       (cheshire.core/generate-string)
       (println)))

out.json

{
  "time": "2015-06-15T10:34:06Z",
  "topic": "Generating json from clojure",
  "numbersToTake": 2,
  "letsNestIt": {
    "someNumbers": [0.7466840252937216, 0.5611557121651881]
  },
  "numbersDoubled": [4,6,8]
}