Just looking for a way to control pretty printing, or even printing

I’m trying to output a tagged literal for regexes

Can you give an example?

Of how you would do it on the JVM I mean

What I naively tried was

(extend-protocol fipp.ednize/IEdn
  java.util.regex.Pattern
  (-edn [x]
    (tagged-literal "regex" (pr-str x))))

Let me see if that works on JVM

mm, doesn’t seem to do what I expected

user=> (defmethod print-method java.util.regex.Pattern [v ^java.io.Writer w] (.write w (pr-str (tagged-literal 'regex (.pattern v)))))
#object[clojure.lang.MultiFn 0x6aef4eb8 "clojure.lang.MultiFn@6aef4eb8"]
user=> (clojure.pprint/pprint #"foo")
#regex "foo"

something like this?

You can also postwalk your data first and turn it into a tagged literal maybe, since overriding print-method for core types might not be a good idea. But it might be OK for scripts

I'm surprised bb supports this btw, I didn't expect it :)

OK, I just need to explicitly call fipp.ednize/edn.

what about the above?

postwalk is certainly a viable workaround. ednize isn’t working as it refers to ThreadLocal.

What about the above print-method ?

Oh, sorry missed that. I thought I tried that before. Let me see

It does work on my machine's bb

OK, sorry for the noise. That does indeed work nicely 🙂

No problem, I'm learning something myself too

This could be useful for preserving the old behavior in all other cases:

(def ^:dynamic *print-config* nil)

(def old-method (get-method print-method java.util.regex.Pattern))

(defmethod print-method java.util.regex.Pattern [v ^java.io.Writer w]
  (if *print-config*
    (.write w (pr-str (tagged-literal 'regex (.pattern v))))
    (old-method v w)))

(prn #"foo")
(binding [*print-config* true]
  (prn #"foo"))

awesommmmeee resources!

we have the #graalvm folks and others to thank 🙂