Clojurians Log v2

I’m wondering if the https://github.com/clojure/clojure/blob/59b65669860a1f33825775494809e5d500c19c63/src/clj/clojure/zip.clj#L231-L233 for clojure.zip/next could be misleading to some, it reads: > Moves to the next loc in the hierarchy, depth-first. When reaching the end, returns a distinguished loc detectable via end? If already at the end, stays there. Some people might assume, without more guidance, that the end of the zipper is the last node in the zipper and that calling next at that point will leave the zipper located at the last node. As far I understand it (which may be not far), the Clojure zipper end state is hit when you’ve called next after the last node in the zipper, after which: • the zipper is no longer navigable or updatable. • you can still call root (or node which at this point is equivalent to root), next and end? but otherwise, I think, it is game over.

(require '[clojure.zip :as czip])

(->> [1 2 3]
     czip/vector-zip
     (iterate czip/next)
     (take 10)
     (map (juxt czip/node czip/end?)))
;; => ([[1 2 3] false]
;;     [1 false]
;;     [2 false]
;;     [3 false]
;;     [[1 2 3] true]
;;     [[1 2 3] true]
;;     [[1 2 3] true]
;;     [[1 2 3] true]
;;     [[1 2 3] true]
;;     [[1 2 3] true])

perfect question for ask.clojure

Thanks @ghadi, I shall post it up on ask.clojure.

and yes, I believe you are correct

pretty sure I wrestled with some kind of change around this in the past

This came up for me while digging into a change for rewrite-clj. Its comment/whitespace skipping next and end? treat the last node as end. This could be an appropriate decision the original rewrite-clj authors made, need to think about it a bit - but it lead me to the clojure.zip/next docstring and made me utter “huh!“.