Map is one of the core elements of a functional programming language. Given a function f and an input sequence s, return a lazy sequence of (f x) for each element x in s.

(ns live.test
  (:require [cljs.test :refer-macros [deftest is testing run-tests]]))
  
(defn juxt-map [f s]
  (flatten (keep (juxt f) s)))

(deftest juxt-map-test
  (is (= [3 4 5 6 7]
         (juxt-map inc [2 3 4 5 6])))
  (is (= (repeat 10 nil)
         (juxt-map (fn [_] nil) (range 10))))
  (is (= [1000000 1000001]
         (->> (juxt-map inc (range))
              (drop (dec 1000000))
              (take 2)))
      (= [1000000 1000001]
         (->> (juxt-map inc (range))
              (drop (dec 1000000))
              (take 2)))))

(comment "uncomment to run tests - this may take awhile..."  
 (run-tests))