From: David Brown <caml-list2@davidb.org>
To: "Frédéric Gava" <gava@univ-paris12.fr>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] (int * int) <> int*int ?
Date: Thu, 23 Feb 2006 10:56:24 -0800 [thread overview]
Message-ID: <20060223185624.GA26907@old.davidb.org> (raw)
In-Reply-To: <006101c6389e$9bbbc440$1f570b50@mshome.net>
On Thu, Feb 23, 2006 at 06:28:48PM +0100, Frédéric Gava wrote:
> I understand that it'is force you to have a pair for A and not just a value
> of type pair but why this restriction ? It is not easy to explain why
> int*int <> (int*int).
As others have explained the represenatation is different. The constructed
types themselves can contain multiple values (represented the same way as a
tuple).
Consider
type a = A of int * int
| B of (int * int)
The result of A (3, 4) will be a two element tuple type tagged
appropriately for 'A' (in this case 0).
The result of B (3, 4) will be a one element tuple type tagged for B,
with the single element referring to the two element tuple containing (3,
4).
Because tuples are generally immutable, there is little semantic
difference, but the compiler does have to keep track of which is which. In
most cases I would guess that 'A' would be more efficient (unless there are
lots of larger constructors sharing the same tuple).
Dave
next prev parent reply other threads:[~2006-02-23 18:56 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-23 17:28 Frédéric Gava
2006-02-23 18:33 ` [Caml-list] " Eric Cooper
2006-02-23 19:03 ` Martin Jambon
2006-02-23 19:07 ` Frédéric Gava
2006-02-23 20:15 ` Brian Hurt
2006-02-23 21:30 ` Frédéric Gava
2006-02-23 21:57 ` Brian Hurt
2006-02-23 22:30 ` Frédéric Gava
2006-02-23 22:50 ` Brian Hurt
2006-02-23 23:07 ` Frédéric Gava
2006-02-24 8:38 ` Alessandro Baretta
2006-02-24 12:59 ` Damien Doligez
2006-02-23 18:33 ` Thomas Fischbacher
2006-02-23 18:56 ` David Brown [this message]
2006-02-23 19:24 ` Frédéric Gava
2006-02-23 19:37 ` Frédéric Gava
2006-02-23 19:45 ` Frédéric Gava
2006-02-24 0:01 ` Jacques Garrigue
2006-02-24 0:18 ` Lukasz Stafiniak
2006-02-24 2:17 ` Jacques Garrigue
2006-02-24 13:07 ` Alain Frisch
2006-02-25 17:42 ` Vincent Balat
2006-02-25 18:30 ` Nicolas Pouillard
2006-02-25 19:09 ` Richard Jones
2006-03-01 12:48 ` Nicolas Pouillard
2006-02-25 23:17 ` Christophe TROESTLER
2006-03-01 13:01 ` Nicolas Pouillard
2006-02-27 11:14 ` camlp4 renovation [was: [Caml-list] (int * int) <> int*int ?] Hendrik Tews
2006-02-24 13:39 ` [Caml-list] (int * int) <> int*int ? Nicolas Cannasse
2006-02-24 14:49 ` Frédéric Gava
2006-02-24 8:27 ` also for tagged records? [Was: Re: [Caml-list] (int * int) <> int*int ?] Sebastian Egner
2006-02-24 14:01 ` Thomas Fischbacher
2006-02-23 20:58 ` [Caml-list] (int * int) <> int*int ? Jon Harrop
2006-02-23 21:36 ` Frédéric Gava
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