store/[org.clojure/clojure "1.8.0"] clj::clojure.core/memfn

Official Documentation

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Arities
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   [name & args]

Docstring
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  Expands into code that creates a fn that expects to be passed an
  object and any args and calls the named instance method on the
  object passing the args. Use when you want to treat a Java method as
  a first-class fn. name may be type-hinted with the method receiver's
  type in order to avoid reflective calls.

Source

(defmacro memfn
  "Expands into code that creates a fn that expects to be passed an
  object and any args and calls the named instance method on the
  object passing the args. Use when you want to treat a Java method as
  a first-class fn. name may be type-hinted with the method receiver's
  type in order to avoid reflective calls."
  {:added "1.0"}
  [name & args]
  (let [t (with-meta (gensym "target")
            (meta name))]
    `(fn [~t ~@args]
       (. ~t (~name ~@args)))))

Example 1

Edit
(def *files* (file-seq (java.io.File. "/tmp/")))
;; => #'user/*files*

(count (filter (memfn isDirectory) *files*))
;; => 68

(count (filter #(.isDirectory %) *files*))
;; => 68

Uses on crossclj