A Clojure function to obtain a lazy sequence with all the elements from an arbitrary amount of (potentially lazy!) input sequences ordered by a given function

ordered_combination.clj

(ns ordered-combination)

(defn ordered-combination
  [sort-fn seqs]
  (if (every? empty? seqs)
    '()
    (let [sorted (sort-by #(sort-fn (first %)) seqs)
          chosen (first sorted)
          new-seqs (concat [(rest chosen)] (rest sorted))]
      (concat [(first chosen)]
              (lazy-seq (ordered-combination sort-fn new-seqs))))))
            
;; Example
#_(take 1000
        (ordered-combination
          identity
          (take 10 (repeatedly #(repeatedly (fn [] (Math/random)))))))