clojure ancestors fn

gistfile1.clj

user=> (ancestors (class #{}))
#{clojure.lang.IFn java.lang.Runnable clojure.lang.AFn clojure.lang.Counted clojure.lang.IMeta clojure.lang.IHashEq clojure.lang.IObj clojure.lang.IEditableCollection java.util.Collection java.lang.Object clojure.lang.APersistentSet java.util.concurrent.Callable clojure.lang.IPersistentSet clojure.lang.IPersistentCollection clojure.lang.Seqable java.lang.Iterable java.io.Serializable java.util.Set}
user=> (ancestors (class ""))
#{java.lang.CharSequence java.lang.Comparable java.lang.Object java.io.Serializable}
user=> (doc ancestors)
-------------------------
clojure.core/ancestors
([tag] [h tag])
  Returns the immediate and indirect parents of tag, either via a Java type
  inheritance relationship or a relationship established via derive. h
  must be a hierarchy obtained from make-hierarchy, if not supplied
  defaults to the global hierarchy
nil
user=> (source ancestors)
(defn ancestors
  "Returns the immediate and indirect parents of tag, either via a Java type
  inheritance relationship or a relationship established via derive. h
  must be a hierarchy obtained from make-hierarchy, if not supplied
  defaults to the global hierarchy"
  {:added "1.0"}
  ([tag] (ancestors global-hierarchy tag))
  ([h tag] (not-empty
            (let [ta (get (:ancestors h) tag)]
              (if (class? tag)
                (let [superclasses (set (supers tag))]
                  (reduce1 into1 superclasses
                    (cons ta
                          (map #(get (:ancestors h) %) superclasses))))
                ta)))))
nil
user=>