cl-json:encode-json of local-time not useful

[erjoalgo]

(cl-json:encode-json (local-time:now))
{"day":8845,"sec":63958,"nsec":58418000}

This encoding a Lisp timestamp is rarely useful outside of CL. Encoding as a unix timestamp would be more useful:

(defmethod cl-json:encode-json ((tstamp LOCAL-TIME:TIMESTAMP) &optional (stream t))
  "Encode timestamps as unix timestamps in json."
  (format stream "~A" (local-time:timestamp-to-unix tstamp)))

[rpgoldman]

I just searched the GitHub repo for the string "local-time" and found nothing except this issue. So there's no code in cl-json specifically for handling local-time timestamps. So why is this a CL-JSON issue?

[erjoalgo]

It's not necessarily a CL-JSON issue, nor is it necessarily a local-time issue. Since it's no one's issue, then becomes an issue for users of CL-JSON that happen to be encoding local-time objects. My opinion is that CL-JSON would be more generally useful if it could gracefully handle types that users may commonly encounter, like timestamps, out-of-the-box. But that's just my opinion.

[rpgoldman]

OK, I could imagine that this would be the job of an additional library, we'd call it "cl-json/local-time", that would depend on both "cl-json" and "local-time" (or, one could also imaging a library "local-time/cl-json" that would be an add-on to local-time instead of cl-json), and that would have additional methods for serialization and deserialization, but I don't see an easy way to add a bunch of special purpose data structures to cl-json itself. Unless there's some way to get libraries to present things like timestamps, that are part of the JSON spec. Then it would just be a matter of making local-time spit out Unix timestamps, instead of working with its own data structures.