Clojure lazy primes

lazy-primes.clj

;; Addapted from python generator found at https://zach.se/project-euler-solutions/10/#python

(defn lazy-primes
  "A lazy sequence that yields prime numbers using Eratosthenes Sieve impl."
  ([] (lazy-primes 2 {}))
  ;; n is the number we are checking for primality
  ;; facts maps composite integers to primes
  ([n facts] 
   (if (not (contains? facts n))
     (lazy-seq (cons n ;; yield since its not composite
                     (lazy-primes (inc n)
                                  (assoc facts (* n n) [n])))) ;; and mark first multiple
     (lazy-primes (inc n) (-> (reduce
                               (fn [r p]
                                 (update r (+ p n) conj p))
                               facts
                               (get facts n)) ;; move each witness to next multiple
                              (dissoc n)))))) ;; don't need it anymore