A threading macro for Clojure for use when threading functions which have varying signatures.

test.clj

(deftest customisable-threading
  (is (= "hello" (->>> :a (% {:a :h}) (name %) (cons % "ello") (clojure.string/join %)))))

threading.clj

(defmacro ->>>
  "Threads the expr through the forms. Inserts x in the place of % in the first form, making a list of it if it is not a
  list already. If there are more forms, inserts the first form in place of % in the second form, and so on."
  ([x form] (if (seq? form)
              (with-meta `((fn [~(symbol "%")] (~@form)) ~x) (meta form))
              (list form x)))
  ([x form & more] `(->>> (->>> ~x ~form) ~@more)))