If you make it into a function and use type hints, that should help:
(defn sum [n]
(let [n (int n)]
(loop [ret (long 0) i (int 1)]
(if (< i n)
(recur (+ ret i) (inc i))
ret))))
user=> (time (reduce + (range 1 1000000)))
"Elapsed time: 116.959837 msecs"
499999500000
user=> (time (sum 1000000))
"Elapsed time: 6.151341 msecs"
499999500000
Frantisek
On Jul 15, 1:51 pm, Dragan <[email protected]> wrote:
> Hi,
>
> I am trying to compare the performance of java loops to clojure reduce
> function. Noting special, Since I am just learning.
> Java code is something like:
>
> [code]
> long sum = 0;
> for (int i = 1; i < 1000000; i++ ){
> sum = sum + i;}
>
> [/code]
>
> while in Clojure I used:
>
> [code]
> (reduce + (range 1 i))
> [/code]
>
> Execution time for the Java version is 7 ms, while Clojure needs 60 -
> 160 ms.
> Now, that is expected, since Clojure runs in REPL.
> Next, I tried the gen-class of the Clojure, and called that Class from
> Java (so no REPL involved), but the code haven't speed up at all!
> Am I missing something or such 10x performance penalty is usual for
> such operations?
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