completing

functionsince v0.0-2341 clojure.core/completingEdit
(completing f)
(completing f cf)

Source docstring:
Takes a reducing function f of 2 args and returns a fn suitable for
transduce by adding an arity-1 signature that calls cf (default -
identity) on the result argument.
Source code @ clojurescript:src/main/cljs/cljs/core.cljs
(defn completing
  ([f] (completing f identity))
  ([f cf]
    (fn
      ([] (f))
      ([x] (cf x))
      ([x y] (f x y)))))