Sample from Poisson distribution in Clojure

poisson-sample.clj

(defn poisson
  "Return a function that samples from a Poisson distribution using Knuth's
  algorithm[^1], given `lambda`, the expected number of occurrences per
  interval.

  [^1]: https://en.wikipedia.org/wiki/Poisson_distribution#Random_drawing_from_the_Poisson_distribution"
  ([lambda]
   (poisson lambda (Random.)))
  ([lambda ^Random r]
   (let [l (Math/exp (- lambda))]
     (fn []
       (loop [k (int 0) p (float 1)]
         (let [p (* p (.nextFloat ^Random r))]
           (if (> p l)
             (recur (inc k) p)
             k)))))))