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AW: AW: [Caml-list] generic Hashtbl.to_array
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 Date: 2006-07-25 (16:35) From: Tom Subject: Re: AW: [Caml-list] generic Hashtbl.to_array
```I'm sorry to say that, but I believe that you results are flawed...

If we look at the code of to_array_1 and to_array_5, there is no possibility
that the former was faster... if nothing else, it has an additional if jump
each and every loop. I simply couldn't believe your results.

Upon inspecting your code with Toploop, I found out some flaws...

let h () =
let h = Hashtbl.create 100000 in
for i = 0 to 99999 do            (* <<< not Hashtbl.length h, as it
returns 0 for ampty hashtable *)
Hashtbl.add h (Random.int max_int) (Random.int max_int);
done;
h

let to_array_1 t =
let dummy =  Array.init 0 (fun _ -> raise Not_found) in
fst
(Hashtbl.fold

(fun k v (a, i) ->
if i = 0 then
let a = Array.make (Hashtbl.length t) (k, v) in
(a, 1)           (* <<<<< Not 0, as it causes no progress *)
else (a.(i) <- (k, v); (a, i + 1)))
t (dummy, 0))

I also corrected my implementation:

let mgc = Obj.magic 0      <<< So that the function is executed only once.
let to_array_5 t =
let a =  Array.make (Hashtbl.length t) mgc in
ignore
(Hashtbl.fold (fun k v i -> a.(i) <- (k, v); i + 1) t 0) ;
a

I tried to do some benchmarking, but I do not have much time... anyhow, my
implementation is faster as far as I tested it.

Believe in your dreams!

```