Quick JSON to CSV converter in Clojure, for use with boot-clj

json-to-csv.clj

#!/usr/bin/env boot
;; needs boot-clj

(set-env! :dependencies '[[org.clojure/data.csv "0.1.3"]
                          [org.clojure/data.json "0.2.6"]])
(require '[clojure.data.csv :as csv])
(require '[clojure.data.json :as json])

(defn run [in out]
  (let [data (json/read in)
        all-keys (apply clojure.set/union (map (comp set keys) data))
        sorted-keys (sort (vec all-keys))
        values-fn (fn [m] (mapv m sorted-keys))
        value-rows (map values-fn data)
        header-and-rows (vec (cons sorted-keys value-rows))]
    (csv/write-csv out header-and-rows)))

(defn -main [& args]
  (run *in* *out*))