slightly saner printing for Clojure fns

foo.clj

(defn delegate-printing-for
  "Registers the necessary methods to delegate printing of instances of [class] to [fn]."
  [class fn]
  #?@(:clj [(defmethod print-method class
              [x writer]
              (.write ^java.io.Writer writer (fn x)))
            (defmethod print-dup class
              [x writer]
              (print-method x writer))
            (#'clojure.pprint/use-method
             clojure.pprint/simple-dispatch
             class
             #'clojure.pprint/pprint-simple-default)]))

#?(:clj (delegate-printing-for
          clojure.lang.AFunction
          #(str "#fn["
                (-> % class .getName
                    ; can't bring myself to impl more un-munging than this
                    (.replaceAll "\\$" "/")
                    (.replaceAll "_" "-"))
                " "
                (format "0x%x " (System/identityHashCode %)) "]")))

; #()
; => #object[user$eval27642$fn__27643 0x44356321 "user$eval27642$fn__27643@44356321"]
; 
; vs.
;
; #()
; => #fn[user$eval27696$fn__27697 0x5e1aaa7c]

Good entry point ;)