solution.clj

(defn minmax-by-codepoint
  "Takes a string and outputs the most and least common
  characters along with their total counts. In the event of a
  tie, return the character with the lowest code point"
  [s]
  (->> (frequencies s)
       ((juxt (partial sort-by (fn [[c cnt]] [cnt c]))
              (partial sort-by (fn [[c cnt]] [(- cnt) c]))))
       (map first)))

(comment
  (= [[\d 1] [\i 7]]
     (minmax-by-codepoint "supercalifragilisticexpialidocious"))
  (= [[\space 1] [\c 3]]
     (minmax-by-codepoint "technicolor dreamcoat")))

not english.

Beautiful!

Beautiful indeed. This is what a solution to this kind of problem should look like.