contains? returns false for existing set item.

[dimovich]

(require '[me.tonsky.persistent-sorted-set :as pset])


(defn update-index [index-data all-data syms]
  (let [cmp-fn (fn [sym1 sym2]
                 (compare (get-in all-data [sym1 :index])
                          (get-in all-data [sym2 :index])))]
    (->>  syms
          (reduce (fn [index-data sym]
                    (-> index-data
                        (pset/disj sym cmp-fn)
                        (pset/conj sym cmp-fn)))
                  (or (not-empty index-data) (pset/sorted-set-by cmp-fn))))))



(def data1 {"Sasha" {:index 0}})

(def data2 {"Sasha"  {:index 0}
            "Misha"  {:index 436},
            "Vanea"  {:index 451}})


(def index (-> (update-index nil data1 ["Sasha"])
               (update-index     data2 ["Misha" "Vanea"])))
;; => #{"Sasha" "Misha" "Vanea}
    
(contains? index "Sasha"))
;; => false

contains? returns false, even though index has item "Sasha".

[Nikita Prokopov]

I guess conj/disj with compare are confusing. They allow you to use different compare function only for the duration of single operation, but do not change the compare function that set itself uses by default. Set will always use the one specified on creation. In your case it’s a cmp-fn closed over data1

[dimovich]

@tonsky Thank you for clarifying. Is it possible to update the cmp-fn specified on creation? Or maybe have option to specify the cmp-fn when calling contains?.

[Nikita Prokopov]

that would require re-sorting the set. So just create a new one