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Message-ID: <4726E433.7060408@frisch.fr>
Date: Tue, 30 Oct 2007 08:58:43 +0100
From: Alain Frisch <alain@frisch.fr>
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To: skaller <skaller@users.sourceforge.net>
Cc: Julien Moutinho <julien.moutinho@gmail.com>,
	caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Preferred Way to Split a List
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X-Spam: no; 0.00; frisch:01 frisch:01 wrote:01 rec:01 caml-list:01 alain:01 alain:01 argument:02 match:02 slower:02 let:03 let:03 split:08 split:08 maybe:10 

skaller wrote:
> The fastest way is:

How can you be so sure? Do you have a proof or some intuitive argument?
Or maybe you tried all the possible other implementations? The following 
should not be that much slower (I did not try it, though, and of course, 
it is not tail-rec):

let split l n =
   let l2 = ref [] in
   let rec aux l n =
     if n = 0 then (l2 := l; [])
     else match l with
       | [] -> []
       | hd :: tl -> hd :: (aux tl (n - 1))
   in
   let l1 = aux l n in
   (l1, !l2)


Alain