From: Christophe Raffalli <christophe.raffalli@univ-savoie.fr>
To: Julien Verlaguet <julien.verlaguet@gmail.com>
Cc: Damien Doligez <damien.doligez@inria.fr>,
OCaml List <caml-list@yquem.inria.fr>
Subject: Re: [Caml-list] tip for tail recursive map
Date: Mon, 02 Nov 2009 21:04:37 +0100 [thread overview]
Message-ID: <4AEF3B55.2060604@univ-savoie.fr> (raw)
In-Reply-To: <a01563690911021156g752f6f5fud3e6bb53eb922fd8@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2752 bytes --]
Julien Verlaguet a écrit :
> Thanks for the tip !
>
> I used this trick on every function of the List module and didn't try to
> go a step further in specific cases.
> Main problem being List.fold_right ... I couldn't figure out a way to
> encode a more efficient continuation encoding
> than the good old CPS, any ideas ?
reverse the list before and then to a fold_left ?
Cheers,
Christophe
>
> Thanks
>
> 2009/11/2 Damien Doligez <damien.doligez@inria.fr
> <mailto:damien.doligez@inria.fr>>
>
>
> On 2009-10-23, at 21:55, pikatchou pokemon wrote:
>
> I know this topic has been discussed several times, but I don't
> think I have seen the solution I use for functions of the List
> module which are not tail recursive.
> I thought sharing the tip could be nice.
> I will take an example, List.map.
> When rewritten in CPS map becomes:
>
> let rec map k f = function
> | [] -> k []
> | x :: rl -> map (fun res -> k ((f x) :: res)) f rl
>
>
> You can do better with an ad-hoc encoding of the continuation
> instead of using closures:
>
>
> let rec map k f = function
> | [] -> List.rev k
> | x :: rl -> map (f x :: k) f rl
> ;;
>
> The memory footprint is smaller, and you spend much less time
> invoking closures.
>
> Note that I haven't bothered benchmarking these two functions.
>
> -- Damien
>
> _______________________________________________
> Caml-list mailing list. Subscription management:
> http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list
> Archives: http://caml.inria.fr
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
>
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Caml-list mailing list. Subscription management:
> http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list
> Archives: http://caml.inria.fr
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs
--
Christophe Raffalli
Universite de Savoie
Batiment Le Chablais, bureau 21
73376 Le Bourget-du-Lac Cedex
tel: (33) 4 79 75 81 03
fax: (33) 4 79 75 87 42
mail: Christophe.Raffalli@univ-savoie.fr
www: http://www.lama.univ-savoie.fr/~RAFFALLI
---------------------------------------------
IMPORTANT: this mail is signed using PGP/MIME
At least Enigmail/Mozilla, mutt or evolution
can check this signature. The public key is
stored on www.keyserver.net
---------------------------------------------
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 260 bytes --]
next prev parent reply other threads:[~2009-11-02 20:04 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-23 19:55 pikatchou pokemon
2009-11-02 10:33 ` [Caml-list] " Damien Doligez
2009-11-02 19:56 ` Julien Verlaguet
2009-11-02 20:04 ` Christophe Raffalli [this message]
2009-11-03 1:29 ` Yaron Minsky
2009-11-02 20:00 ` Christophe Raffalli
2009-11-02 23:30 ` Jon Harrop
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4AEF3B55.2060604@univ-savoie.fr \
--to=christophe.raffalli@univ-savoie.fr \
--cc=caml-list@yquem.inria.fr \
--cc=damien.doligez@inria.fr \
--cc=julien.verlaguet@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).