A sample Janet program to read a "special" csv file, convert the data into weighted options, and randomly pick one

sample.janet

(math/seedrandom (os/cryptorand 8))
(math/random)

(defn read-raw-text
  [path]
  (-> path
      (file/open :r)
      (file/read :all)))

(defn read-special-csv-lines
  [raw-text]
  (->> raw-text
       (|(string/split "\n" $))
       (map string/trim)
       (|(slice $ 1 -2))))

(defn parse-special-csv-line
  [csv-line]
  (->> csv-line
       (string/split ",")
       (map string/trim)))

(defn infere-option
  [values_]
  (def [name weight] values_)
  {:name name
   :weight (parse weight)})

(defn pick-an-option
  [options]
  (let [weights (map |(get $ :weight) options)
        weights-sum (sum weights)
        weights-accumulated (accumulate2 + weights)
        random-threshold (* weights-sum (math/random))
        picked-option-index (find-index
                              (fn [weight]
                                (>= weight random-threshold))
                              weights-accumulated)
        picked-option (options picked-option-index)]
    picked-option))

(defn printf-picked-option
  [option]
  (string "The picked option: "
          (get option :name)))

(def path "/tmp/input.csv")
(->> path
     read-raw-text
     read-special-csv-lines
     (map parse-special-csv-line)
     (map infere-option)
     pick-an-option
     printf-picked-option)