protocolsince v0.0-927 clojure.lang/AssociativeEdit
implemented for BlackNode MapEntry ObjMap PersistentArrayMap PersistentHashMap PersistentTreeMap PersistentVector RedNode Subvec

Source docstring:
Protocol for adding associativity to collections.
Source code @ clojurescript:src/main/cljs/cljs/core.cljs
(defprotocol IAssociative
  (^boolean -contains-key? [coll k]
    "Returns true if k is a key in coll.")
  #_(-entry-at [coll k])
  (^clj -assoc [coll k v]
    "Returns a new collection of coll with a mapping from key k to
     value v added to it."))