functionsince v0.0-2261 clojure.core/mix-collection-hashEdit
(mix-collection-hash hash-basis count)

Source docstring:
Mix final collection hash for ordered or unordered collections.
hash-basis is the combined collection hash, count is the number
of elements included in the basis. Note this is the hash code
consistent with =, different from .hashCode.
See http://clojure.org/data_structures#hash for full algorithms.
Source code @ clojurescript:src/main/cljs/cljs/core.cljs
(defn ^number mix-collection-hash
  [hash-basis count]
  (let [h1 m3-seed
        k1 (m3-mix-K1 hash-basis)
        h1 (m3-mix-H1 h1 k1)]
    (m3-fmix h1 count)))