Thanks to @seancorfield: "We wrote our own `condp->` and `condp->>` macros that thread through the predicate as well as the expression." -- https://clojurians-log.clojureverse.org/clojure/2017-06-01.html#inst-2017-06-01T04:38:05.966147Z

ext.clj

(defmacro condp->
  "Takes an expression and a set of predicate/form pairs. Threads expr (via ->)
  through each form for which the corresponding predicate is true of expr.
  Note that, unlike cond branching, condp-> threading does not short circuit
  after the first true test expression."
  [expr & clauses]
  (assert (even? (count clauses)))
  (let [g (gensym)
        pstep (fn [[pred step]] `(if (~pred ~g) (-> ~g ~step) ~g))]
    `(let [~g ~expr
           ~@(interleave (repeat g) (map pstep (partition 2 clauses)))]
       ~g)))

(defmacro condp->>
  "Takes an expression and a set of predicate/form pairs. Threads expr (via ->>)
  through each form for which the corresponding predicate is true of expr.
  Note that, unlike cond branching, condp->> threading does not short circuit
  after the first true test expression."
  [expr & clauses]
  (assert (even? (count clauses)))
  (let [g (gensym)
        pstep (fn [[pred step]] `(if (~pred ~g) (->> ~g ~step) ~g))]
    `(let [~g ~expr
           ~@(interleave (repeat g) (map pstep (partition 2 clauses)))]
       ~g)))

(defn flip
  "Like partial except you supply everything but the first argument.
  Also like Haskell's flip for single arity call."
  ([f] (fn [b a] (f a b)))
  ([f b] (fn [a] (f a b)))
  ([f b c] (fn [a] (f a b c)))
  ([f b c d & more]
   (fn [a] (apply f a b c d more))))