Lazy map implementation for use when doing side-effectual things by mapping some fn with side-effects to a seq.

lazy-map.clj

(defn lazy-map [f coll]
  (if (seq coll)
    (lazy-seq (cons (f (first coll)) (lazy-map f (rest coll))))
    nil))

;; The difference
clj-print.core> (type (seq (map print (range 50))))
012345678910111213141516171819202122232425262728293031
clojure.lang.ChunkedCons

clj-print.core> (type (seq (lazy-map print (range 50))))
0
clojure.lang.Cons