Clojure's maps: are keys and vals in same order?

问题

Is it ok to rely on (= m (zipmap (keys m) (vals m))) in Clojure 1.3+?

Having this behavior makes for slightly more readable code in some situations, eg

(defn replace-keys [smap m]
  (zipmap (replace smap (keys m)) (vals m)))

vs.

(defn replace-keys [smap m]
  (into {} (for [[k v] m] [(smap k k) v]))

回答1:

I can confirm (officially) that the answer to this is yes. The docstrings for keys and vals were updated in Clojure 1.6 to mention this (see http://dev.clojure.org/jira/browse/CLJ-1302).

回答2:

Yes, lots of clojure would break if that changed.

Maps are stored as trees and both functions walk the same tree in the same order.

来源：https://stackoverflow.com/questions/10772384/clojures-maps-are-keys-and-vals-in-same-order