So the most used functions on Clojure map and filter have been modified to return transducers (composable algorithmic transformations), if not called with a collection. That means:
(map inc) returns a transducer and so does
The advantage: the functions can be composed into a single function by comp , which means traversing the collection just once. Saves run time by over 50% in some scenarios.
(def composed-fn (comp (map inc) (filter odd?)))
;; So instead of doing this: (->> [1 8 3 10 5] (map inc) (filter odd?)) ;; Output [9 11] ;; We do this: (into  composed-fn [1 8 3 10 5]) ;; Output: [9 11]