Option to print type info


  • Type: Enhancement Enhancement
  • Status: Open Open
  • Priority: Minor Minor
  • Resolution: Unresolved
  • Affects Version/s: None
  • Fix Version/s: None
  • Component/s: None
  • Labels:


I've had an issue with defrecord-types being converted into ordinary maps somewhere, which was relatively hard to track down inside a deep structure since they are pprinted as the same thing by default.
The following code patches into the pprint dispatch and prints the type around values; it turned out to be quite useful, but feels hackish.
Maybe something like that would be useful to integrate into clojure.pprint directly (there are a number of cosmetic options already), i.e. into clojure.pprint/write-out.

Only printing (type) may not be enough in some cases; so an option to print all metadata would be nice.
Maybe something like :metadata nil as default, :metadata :type to print types (but also for non-IMetas, using (type) and :metadata true to print metadata for IMetas using (meta).

(defn pprint-with-type
  ([object] (pprint object *out*))
  ([object writer]
   ; keep original dispatch.
   ; calling it directly will print only that object,
   ; but return to our dispatch for subobjects.
   (let [dispatch clojure.pprint/*print-pprint-dispatch*]
     (binding [clojure.pprint/*print-pprint-dispatch*
               (fn [obj]
                 (if (instance? clojure.lang.IMeta obj)
                   (do (print "^{:type ")
                       (dispatch (type obj))
                       (print "} ")
                       (clojure.pprint/pprint-newline :fill)
                       (dispatch obj))
                   (do (print "(^:type ")
                       (dispatch (type obj))
                       (print " ")
                       (clojure.pprint/pprint-newline :fill)
                       (dispatch obj)
                       (print ")"))))]
       (clojure.pprint/pprint object writer)))))


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