From: Bill Wood <william.wood3@comcast.net>
To: Martin Chabr <martin_chabr@yahoo.de>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Avoiding shared data
Date: Sun, 25 Sep 2005 19:23:59 -0500 [thread overview]
Message-ID: <1127694239.1060.23.camel@localhost> (raw)
In-Reply-To: <20050925213202.32862.qmail@web26805.mail.ukl.yahoo.com>
. . .
> I need to process arrays of pairs of integers and
> records ((int * record) array) in which all elements
> must be updated individually, which means that
> unshared data structures must be used. For arrays of
> arrays I can produce unshared data by using the
> library functions Array.copy and Array.append to
> append the individual arrays into the embedding array.
> It works, the low level arrays can be updated
> individually. But I cannot use the same scheme to the
> array of the (int * record) structures, because I do
> not know how to copy these structures to dissolve the
> sharing. I do not even know how to copy records. It
> seems to me that this problem occurs always when I
> want to produce an array of data with a fixed
> structure automatically (rather than entering the
> array [| ... |] by hand at the top level interpreter
> using constants only). How can I produce completely
> unshared structures?
Funny you should mention it, I wrestled with this just this week. I'm
building a square, i.e. array of N elements, each of which is itself an
array of N cells, where a cell is a record with several fields. Here's
the way I did it:
1) I defined a function initial_cell : unit -> cell as
let initial_cell () =
let c = {field1 = val1; ...; fieldN = valN} in
c;;
2) I defined a function initial_row : int -> cell array as:
let initial_row n = Array.init n (fun i -> initial_cell ());;
3) I defined a function initial_square : int -> cell array array by:
let initial_square n = Array.init n (fun i -> initial_row ());;
I think the essential point is the Array.init function; since it expects
to set the i-th element of the new array to (f i) for unknown f, it
can't make an array that shares.
I hope this is of some help,
-- Bill Wood
bill.wood@acm.org
next prev parent reply other threads:[~2005-09-26 0:24 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-25 21:32 Martin Chabr
2005-09-26 0:23 ` Bill Wood [this message]
2005-09-26 7:57 ` [Caml-list] " Claudio Sacerdoti Coen
2005-09-26 8:17 ` William Lovas
2005-09-26 21:07 ` Ant: " Martin Chabr
2005-09-26 22:08 ` Jon Harrop
2005-09-30 22:57 ` Oliver Bandel
2005-10-01 0:07 ` Pal-Kristian Engstad
2005-10-01 5:46 ` Bill Wood
2005-10-01 8:27 ` Wolfgang Lux
2005-10-01 18:02 ` Wolfgang Lux
2005-10-01 21:50 ` Ant: " Martin Chabr
2005-10-01 12:34 ` Oliver Bandel
2005-10-01 13:58 ` Bill Wood
2005-10-01 21:05 ` Ant: " Martin Chabr
2005-10-03 0:41 ` skaller
2005-10-03 1:13 ` Seth J. Fogarty
2005-10-03 13:09 ` Thomas Fischbacher
2005-10-03 14:57 ` skaller
2005-10-03 20:03 ` Ant: " Martin Chabr
2005-10-03 20:25 ` Thomas Fischbacher
2005-10-03 21:08 ` Jon Harrop
2005-10-04 18:06 ` Ant: " Martin Chabr
2005-10-04 18:32 ` Jon Harrop
2005-10-04 2:53 ` skaller
2005-10-04 16:15 ` Brian Hurt
2005-10-04 16:47 ` FP/IP and performance (in general) and Patterns... (Re: [Caml-list] Avoiding shared data) Oliver Bandel
2005-10-04 22:38 ` Michael Wohlwend
2005-10-05 0:31 ` Jon Harrop
2005-10-04 22:39 ` Christopher A. Watford
2005-10-04 23:14 ` Jon Harrop
2005-10-05 12:10 ` Oliver Bandel
2005-10-05 13:08 ` Jon Harrop
2005-10-05 15:28 ` skaller
2005-10-05 20:52 ` Ant: " Martin Chabr
2005-10-05 23:21 ` Markus Mottl
2005-10-06 16:54 ` brogoff
2005-10-05 0:45 ` Brian Hurt
2005-10-04 18:09 ` Ant: Re: Ant: Re: Ant: Re: Ant: Re: [Caml-list] Avoiding shared data Martin Chabr
2005-10-05 8:42 ` skaller
2005-10-05 11:14 ` Andrej Bauer
2005-10-01 21:36 ` Ant: Re: Ant: " Martin Chabr
2005-10-03 11:51 ` getting used to FP-programming (Re: Ant: Re: Ant: Re: [Caml-list] Avoiding shared data) Oliver Bandel
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