An example of logging and sanitizing server parsers exceptions

parser.clj

(defn handle
  [env params]
  (let [p (parser {:read   readf
                   :mutate mutatef})
        result (p env params)
        errors (->> result
                    (filter (fn [[k v]] (instance? Throwable v))))]
    (if (seq errors)
      (do
        (doseq [[req res] errors]
          (error res))
        (->> result
             (map (fn [[k v]]
                    [k (if (instance? Throwable v)
                         :operation-failed
                         v)]))
             (into {})))
      result)))