Clojure Q&A - Recent questions tagged update-vals

update-vals documentation string has a typo

Fri, 15 Sep 2023 22:12:07 +0000

(doc update-vals)
-------------------------
clojure.core/update-vals
([m f])
  m f => {k (f v) ...}

  Given a map m and a function f of 1-argument, returns a new map where the keys of m
  are mapped to result of applying f to the corresponding values of m.

Says "...returns a new map where the >>>keys<<< of m are mapped to...". This should be "values," not "keys." Probably a cut/paste holdover from the update-keys doc string.

`update-keys` and `update-vals` missing the `& args` from `update`

Tue, 09 Aug 2022 15:03:31 +0000

The & args in update, swap! and etc are very ergonomic and compose really well, so I was surprised to learn that update-keys and update-vals don't have that, they're only [m f].

What is the reason for this?

I think adding & args to these functions would be more consistent with the existing core functions and help avoid anon functions where not needed.

`update-vals` not preserving sorted maps?

Wed, 27 Jul 2022 08:35:05 +0000

Hello! We recently found that when applying update-vals to a sorted map, it's converted back into an unsorted array/hash map due to the collection not being transientable. Example given below. As a note, this differs from medley/map-vals which preserves sorting and which we were using for this functionality previously to 1.11.

Is this intended behavior? If so, I'd be curious about the intent behind it :) Thanks!

user> (def m (sorted-map :a 0 :b 0))
;; => #'user/m
user> (type m)
;; => clojure.lang.PersistentTreeMap
user> (type (update-vals m inc))
;; => clojure.lang.PersistentArrayMap
user> (type (medley.core/map-vals inc m))
;; => clojure.lang.PersistentTreeMap