feedback on file parsing with Clojure

[AndyK]

hello,

i'm looking for some feedback on how i've used Clojure to do some file parsing

still getting the hang of Clojure ways of thinking and i'd love to hear any advice on how to improve what i've done

for example, i'm guessing the way i've used cond blocks is a bit sketchy - at that point, i was kind of in a just-get-it-done mindset 

the file being parsed is here

https://github.com/AndyKriger/i-ching/blob/master/clojure/resources/i-ching.html

the code doing the parsing is here

https://github.com/AndyKriger/i-ching/blob/master/clojure/src/i_ching/parser.clj

the output is here (a browser JSON viewer is advised)

https://raw.githubusercontent.com/AndyKriger/i-ching/master/clojure/resources/i-ching.json

thank you for any help

a

[Justin Smith]

The primary suggestion I'd make here is to replace the doseq/reset! construction in your main loop with reduce using a hash-map accumulator representing each value you are updating with a separate key. This isn't just more idiomatic, it also performs better.

Instead of:

(let [hexagrams (atom (sorted-map))

      state (atom :do-nothing)

      current-hexagram (atom {})]

  (doseq [line (line-seq rdr)]

    (let [state-machine (@state PRETTY-STATE-MACHINE)

          line-match (re-matches (:regex state-machine) line)

          [new-state new-hexagram] ((:handler state-machine) line-match @current-hexagram)]

      (reset! state new-state)

      (reset! current-hexagram new-hexagram)

      (swap! hexagrams assoc (:king-wen-number new-hexagram) new-hexagram))))

something like:

(reduce (fn [acc line]

          (let [{:keys [state hexagrams current-hexagram]} acc

                state-machine (state PRETTY-STATE-MACHINE)

                line-match (re-matches (:regex state-machine) line)

                [new-state new-hexagram] ((:handler state-machine) line-match current-hexagram)]

            {:state new-state

             :current-hexagram new-hexagram

             :hexagrams (assoc (:king-wen-number new-hexagram) new-hexagram)}))

        (line-seq rdr))

as a more minor issue, we idiomatically use [a b] instead of (vector a b)

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