If you check his remarks from Spec-ulation (https://www.youtube.com/watch?v=oyLBGkS5ICk https://www.youtube.com/watch?v=oyLBGkS5ICk), he also thinks just plain

If you check his remarks from Spec-ulation (https://www.youtube.com/watch?v=oyLBGkS5ICk https://www.youtube.com/watch?v=oyLBGkS5ICk), he also thinks just plain old libraries should not remove or change functionality, but only accrete. If you want to make a breaking change, you should change the name of the library. You can see this philosophy in practice with clojure.spec.alpha-2: https://github.com/clojure/spec-alpha2 https://github.com/clojure/spec-alpha2