This the code: https://github.com/clojure/clojure/commit/86a158d0e0718f5c93f9f2bb71e26bc794e7d58e

There's some Java interop in there, so not sure how easy a port for Joker would be.

Thanks, that's helpful. Seems like it'd be a nontrivial amount of work to add to Joker -- especially the tap stuff.