From: David House <dhouse@janestreet.com>
To: Damien Guichard <alphablock@orange.fr>
Cc: Caml Mailing List <caml-list@inria.fr>
Subject: Re: [Caml-list] How much optimized is the 'a option type ?
Date: Fri, 17 Jan 2014 07:55:42 +0000 [thread overview]
Message-ID: <CAK=fH+jyvnFzrHTLf7HUu+MOZVFzw0-d61zY8rVXypZJdknHUA@mail.gmail.com> (raw)
In-Reply-To: <523666417617602473@orange.fr>
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It behaves identically to that type.
It is just like any other sum type. However, due to the way that sum types
are represented in memory, it is not that inefficient. The only thing that
makes it less efficient than a C pointer is the header block (necessary for
the GC). An option value always takes two words: one for the header, and
then either a pointer or a word that means "None".
On 17 January 2014 07:35, Damien Guichard <alphablock@orange.fr> wrote:
> Hello,
>
> Compared to the code :
>
> type 'a option = None | Some of 'a
>
> How do an 'a option value performs ?
> Any allocation saved ?
> Any indirection removed ?
>
> Is 'a option just like any sum type ?
> Or is 'a option more like an ANSI C pointer type ?
>
> Regards,
>
> Damien Guichard
>
>
>
> --
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next prev parent reply other threads:[~2014-01-17 7:55 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-01-17 7:35 Damien Guichard
2014-01-17 7:55 ` David House [this message]
2014-01-17 8:16 ` Julien Blond
2014-01-17 8:40 ` David House
2014-01-17 9:10 ` Gabriel Scherer
2014-01-17 9:22 ` Simon Cruanes
2014-01-17 17:57 ` Gerd Stolpmann
2014-01-18 1:35 ` Jon Harrop
2014-01-19 6:19 ` oleg
2014-01-21 1:51 ` Francois Berenger
2014-01-18 1:01 ` Jon Harrop
2014-01-24 10:06 ` Alain Frisch
2014-01-24 10:16 ` Alain Frisch
2014-01-24 13:32 ` Yaron Minsky
[not found] ` <CAK=fH+jfi=GsMYBZzmuo=V5UAWimyxiiamY2+DkLg6F0i8XHGw@mail.gmail.com>
2014-01-17 9:11 ` David House
2014-01-17 11:23 ` Jonathan Kimmitt
2014-01-17 13:46 ` Nicolas Braud-Santoni
2014-01-17 13:56 ` Frédéric Bour
2014-01-17 14:02 ` Yaron Minsky
2014-01-17 14:09 ` Simon Cruanes
2014-01-17 22:52 ` Yaron Minsky
2014-01-18 1:37 ` Jon Harrop
2014-01-17 14:24 ` Gabriel Scherer
2014-01-17 22:29 ` Yaron Minsky
2014-01-18 1:27 ` Jon Harrop
2014-01-18 1:18 ` Jon Harrop
2014-01-20 10:16 ` Goswin von Brederlow
2014-01-20 11:23 ` Jonathan Kimmitt
2014-01-21 2:05 ` Francois Berenger
2014-01-22 21:22 ` Jon Harrop
2014-01-22 21:26 ` Jon Harrop
2014-01-23 9:29 ` Goswin von Brederlow
2014-01-23 23:20 ` Jon Harrop
2014-01-23 23:28 ` Yotam Barnoy
2014-01-24 8:22 ` Jon Harrop
2014-01-24 8:34 ` Andreas Rossberg
2014-01-24 16:56 ` Jon Harrop
2014-01-27 15:29 ` Goswin von Brederlow
2014-01-27 16:18 ` Yotam Barnoy
2014-01-29 7:56 ` Goswin von Brederlow
2014-01-29 8:32 ` Jon Harrop
2014-01-29 16:11 ` Yotam Barnoy
2014-01-30 18:43 ` Yotam Barnoy
2014-02-01 15:58 ` Goswin von Brederlow
2014-01-30 21:31 ` Jon Harrop
2014-01-30 21:43 ` Yotam Barnoy
2014-01-31 8:26 ` Jon Harrop
2014-02-01 15:40 ` Goswin von Brederlow
2014-01-27 10:03 ` Goswin von Brederlow
2014-01-17 14:36 ` Markus Mottl
2014-01-17 15:49 ` Yotam Barnoy
2014-01-17 16:22 ` Markus Mottl
2014-01-20 10:09 ` Goswin von Brederlow
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