when_letp.clj

(defmacro when-letp
  {:style/indent 2}
  [pred bindings & body]
  (if (empty? bindings)
    `(do ~@body)
    (let [[[binding expr] more] (split-at 2 bindings)]
      `(let [temp# ~expr
             pred# ~pred]
         (when (pred# temp#)
           (let [~binding temp#]
             (when-letp pred# ~(vec more) ~@body)))))))

(comment
  (let [x (calc-x)]
    (when (pred? x)
      (do-something-to x)))

  (when-letp pred? [x (calc-x)]
    (do-something-to x))

  (when-letp number? [x 42]
    (inc x))
  )