Why Not a Function #16: interval-in

(require '[clj-time.core :as t])

(defn interval-in
  [start end in]
  (if (t/after? end start)
    (in (t/interval start end))
    (- (in (t/interval end start)))))

interval-in serves as a wrapper around clj-time’s interval. The problem with the original interval is that it does not return negative values. It simply throws an exception. Our alternative returns a negative number if start is after end.

(def now (t/now))
=> #'user/now

(def hour-later (t/plus now (t/hours 1)))
=> #'user/hour-later

(interval-in now hour-later t/in-hours)
=> 1

(interval-in hour-later now t/in-hours)
=> -1

Written on April 1, 2020