Clojure script to extract some fields from a edn-file and store it as a CSV file

edn-to-csv.clj

#!/usr/bin/env boot

(require '[clojure.java.io :as io])
(require '[clojure.edn     :as edn])

(def fname "/path/to/clojure-edn.clj")
(def ofname "/path/to/out.csv")

;; out-format:
;; "keykeykey", "valvalval"

(defn mkcsv
  [m]
  (str
    "\""
    (:key m)
    "\",\""
    (get-in m [:value :another-key])
    "\"\n"))


(defn -main [& args]
  (let [in (-> fname io/file io/reader)
        out (-> ofname io/file io/writer)]
    (try
      (loop [i 0]
        (when-some [line (.readLine in)]
          (let [edn (edn/read-string line)]
            ;; write
            (.write out (mkcsv edn)))
          (when (zero? (mod i 100))
            (.flush out))
          (recur (inc i))))
      (catch Exception ex
        (println "Exception occured: " ex))
      (finally
        (.close in)
        (.close out)))))