clojure.core/reverse

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Type: function Added: Clojure 1.0 Examples: 3 Runnable: 2

([coll])

Returns a seq of the items in coll in reverse order. Not lazy.

Examples

by gstamp on 2010-07-28 ▶

(reverse '(1 2 3)) (3 2 1)

by rosineygp on 2019-09-14 ▶

(reverse "clojure") ; (\e \r \u \j \o \l \c) (apply str (reverse "clojure")) ; "erujolc"

by Crowbrammer on 2021-02-19 . May have evaluation errors. ▶

;; Comparison between `reverse` and `rseq` for a vector. (def nums (vec (range 1000000))) (time (reverse nums)) ;; "Elapsed time: 30.1222 msecs" (time (rseq nums)) ;; "Elapsed time: 0.0664 msecs"

Note by gstamp

If you've got a vector rseq is a good option instead of reverse.

Note by Crowbrammer

For vectors, rseq is to reverse what peek is to last. rseq reverses in constant time (!) where reverse is in linear time, as it appears to pull everything into a new seq, one at a time instead of ... reversing the keys? I don't know the implementation details, but I do know that rseq is magnitudes faster than reverse for vectors and sorted maps.

See also

• clojure.core/rseq (2)

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