From: Pal-Kristian Engstad <engstad@naughtydog.com>
To: Oleg <oleg_inconnu@myrealbox.com>, caml-list@inria.fr
Subject: Re: [Caml-list] Why is (@) written in O'Caml?
Date: Thu, 5 Dec 2002 13:16:08 -0800 [thread overview]
Message-ID: <200212051316.08952.engstad@naughtydog.com> (raw)
In-Reply-To: <200212051547.09337.oleg_inconnu@myrealbox.com>
On Thursday 05 December 2002 12:47 pm, Oleg wrote:
> let rec (@) l1 l2 =
> match l1 with
> [] -> l2
>
> | hd :: tl -> hd :: (tl @ l2)
>
> The O'Caml implementation of (@) is recursive and not tail-recursive. All
> one really has to do during "append" is copy l1 and set the last element's
> CDR to l2. I can see why this can not be done in O'Caml itself, but since
> (@) is such a common operation, I'm wondering why it was decided to
> implement it inefficently in O'Caml itself?
You say you want to copy l1 and then set the last element of tail to l2? But,
that is _exactly_ what the function above does!
let copy l1 =
match l1 with
[] -> []
| hd :: tl -> hd :: copy tl
Right? So, the only change is the extra argument l2, that is being appended
onto the list when l1 is empty.
PKE.
--
_
\`. Pål-Kristian Engstad, Senior Software Engineer,
\ `| Naughty Dog, Inc., 1315 3rd Street Promenade,
__\ |`. Santa Monica, CA 90046, USA. (310) 752-1000 x799.
/ /o mailto:engstad@naughtydog.com http://www.naughtydog.com
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/ ,' Hang-gliding Rulez!
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next prev parent reply other threads:[~2002-12-05 21:14 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-12-05 20:47 Oleg
2002-12-05 21:16 ` Pal-Kristian Engstad [this message]
2002-12-05 21:24 ` Oleg
2002-12-05 21:55 ` Pal-Kristian Engstad
2002-12-05 23:27 ` Oleg
2002-12-05 23:53 ` Pal-Kristian Engstad
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