eval-macro.clj

(defn in?
  [xs x]
  (some #(= x %) xs))

(defn unwrap
  [xs]
  (if (and (list? xs) (list? (first xs)) (nil? (next xs)))
    (first xs)
    xs))

(defn replace-op
  [operators expr]
  (let [[left op right & rest] expr]
    (println (str "left: " left ", op: " op ", right: " right ", rest: " rest))
    (cond
      (nil? op) (list left)
      (in? operators op) (replace-op operators (cons (list op left right) rest))
      :else (concat (list left op) (replace-op operators (cons right rest))))))


(defmacro eval-arithmetic
  [expression]
  (->> expression
      (replace-op ['* '/])
      (replace-op ['+ '-])
       unwrap))