On Oct 18, 3:07 pm, Jürgen Hötzel <juer...@hoetzel.info> wrote:
> > (defn sum [arr]
> > (loop [i (int 0) s (int 0)]
> > (if (= i *N*) s
>
> ^^^^^^^^^^^
>
> You still doing non-primitive ops here.
Indeed, I overlooked that.
But this was not the main cause of the trouble.
> Also Check for areduce:
>
> (defn sum [^ints arr]
> (areduce arr i ret (int 0)
> (unchecked-add-int ret (aget arr i))))
This code works at the top speed.
(the time with Clojure-1.2 now is ~17 msec, same as for Java, and
with Clojure-1.3-alpha it's 67 msec)
By comparing my code with areduce macro I've found
what was the problem -- it's a '=' operator, which I used
instead of '>='.
Therefore this version of areduce is ~10 times slower
(in spite of being equivalent logically with the original one):
(defmacro areduce-slow
"Reduces an expression across an array a, using an index named idx,
and return value named ret, initialized to init, setting ret to the
evaluation of expr at each step, returning ret."
{:added "1.0"}
[a idx ret init expr]
`(let [a# ~a]
(loop [~idx (int 0) ~ret ~init]
(if (= ~idx (alength a#)) ;; '=' instead of '>=' (but original
areduce uses '<' and ~ret in the 'else' branch)
~ret
(recur (unchecked-inc ~idx) ~expr)))))
Is it a bug? Should I report it to the development team?
Thanks a lot for the prompt and informative answer.
Regards,
Dmitriy
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