Clojurians Log v2

I've come up with a solution, but would love to hear from more experienced users.

(defn only-one-key-of [kws]
  (fn [m]
    (not
     (set/subset? kws
                  (into #{} (keys m))))))

(s/def ::some-map
  (s/and
   (s/keys :req [:a]
           :opt [:b :c :d])
   (only-one-key-of [:b :c])))

(comment
  (s/valid? ::some-map {:a 1 :b 2 :c 3})  ;; correctly gives `false`
)

I think that's the right approach

Nice. Thanks for your feedback

small warning: only-one-key-of might be a bit misleading, it won't give the expected result if there are more than 2 keywords

Yes, it was not very well-defined, it also didn't for just one parameter. I've redone the implementation to be more robust now. Thanks for pointing it out though 🙂