(defn safe-merge
  "Like merge, but throws if maps have the same keys but different values."
  [& maps]
  (reduce
   (fn [m [m2k m2v :as re]]
     (if-some [[_ mv :as le] (find m m2k)]
       (if (= mv m2v)
         m
         (throw (ex-info "Attempted to safe-merge maps with conflicting entries"
                         {:left-entry le :right-entry re})))
       (conj m re)))
   (first maps) (apply concat (rest maps))))