Maps an expression across an array a, using an index named idx, and
return value named ret, initialized to a clone of a, then setting
each element of ret to the evaluation of expr, returning the new
array ret.
(def an-array (int-array 25000 (int 0)))
user=> (time (amap ^ints an-array
idx
ret
(+ (int 1)
(aget ^ints an-array idx))))
"Elapsed time: 14.708653 msecs"
;; Note: without type hinting the performance of would not be good.
Source
clojure/core.clj:4566
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(defmacro amap
"Maps an expression across an array a, using an index named idx, and
return value named ret, initialized to a clone of a, then setting
each element of ret to the evaluation of expr, returning the new
array ret."
{:added "1.0"}
[a idx ret expr]
`(let [a# ~a
~ret (aclone a#)]
(loop [~idx 0]
(if (< ~idx (alength a#))
(do
(aset ~ret ~idx ~expr)
(recur (unchecked-inc ~idx)))
~ret))))
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