(ns fourmls.core
    (:gen-class))

  (defn csv-line-to-doubles
    [line]
    (map #(Double. %)
         (clojure.string/split line #",")))

  (defn barf-if-different-lengths
    [s1 s2]
    (if (not= (count s1)
              (count s2))
      (throw (Exception. "Mismatched lengths"))
      s2))

  (defn sum-csv-lines
    [prev curr]
    (if (nil? prev)
      (csv-line-to-doubles curr)
      (->> curr
           csv-line-to-doubles
           (barf-if-different-lengths prev)
           (interleave prev)
           (partition 2)
           (map (partial apply +)))))

  (defn -main
    "I don't do a whole lot ... yet."
    [filename]
    (println
     (clojure.string/join
      ","
      (map str
           (reduce sum-csv-lines
                   nil
                   (->> filename
                        clojure.java.io/reader
                        line-seq))))))