From: Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp>
To: tom7ca@yahoo.com
Cc: williamc@paneris.org, caml-list@inria.fr
Subject: [Caml-list] let mutable (was OCaml Speed for Block Convolutions)
Date: Fri, 08 Jun 2001 08:49:47 +0900 [thread overview]
Message-ID: <20010608084947C.garrigue@kurims.kyoto-u.ac.jp> (raw)
In-Reply-To: <20010607182007.33358.qmail@web11902.mail.yahoo.com>
About the introduction of a let mutable construct,
Tom _ <tom7ca@yahoo.com> wrote
> In any case, whether or not the compiler in the
> current implementation can or cannot do good type
> inference and may or may not be forced to box
> a floating point number, the two constructs mean
> something different to the programmer, and they
> behave differently. In particular "mutable x"
> can never be passed around as a reference, while
> "x = ref ..." can. If not anything else, that
> prevents the programmer from inadvertently inhibiting
> a compiler optimization by passing around a reference.
Not exactly, the compiler may still need to build a reference.
let mutable x = 0 in
List.iter (fun y -> x <- x+y) l;
x
Since x has to be modified in a function called by iter, it must be
wrapped into an actual reference cell.
As the compiler already does a good job at unboxing only locally used
references, let mutable would only be some syntactic sugar (with
exactly the same typing as a reference).
> Besides, the syntax is probably quite a bit more
> natural to imperative programmers anyway.
This is actually the only argument for let mutable.
I would also like such a construct, but I don't know whether its worth
it. The real question is whether let mutable should be allowed at
toplevel, with problems for both answers.
Cheers,
Jacques Garrigue
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next prev parent reply other threads:[~2001-06-07 23:50 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-06-04 13:25 [Caml-list] OCaml Speed for Block Convolutions David McClain
2001-06-04 19:51 ` William Chesters
2001-06-04 20:05 ` Chris Hecker
2001-06-04 20:15 ` David McClain
2001-06-04 22:34 ` Markus Mottl
2001-06-06 20:13 ` William Chesters
2001-06-06 22:29 ` Chris Hecker
2001-06-07 7:42 ` William Chesters
2001-06-05 7:22 ` Chris Hecker
2001-06-06 6:27 ` David McClain
2001-06-04 22:14 ` Tom _
2001-06-04 22:57 ` Chris Hecker
2001-06-05 2:52 ` Brian Rogoff
2001-06-05 15:02 ` Stefan Monnier
2001-06-05 10:48 ` Tom _
2001-06-06 2:03 ` Hugo Herbelin
2001-06-06 4:04 ` Charles Martin
2001-06-06 18:25 ` William Chesters
2001-06-06 18:35 ` William Chesters
2001-06-06 18:40 ` Patrick M Doane
2001-06-07 1:50 ` Hugo Herbelin
2001-06-07 18:20 ` Tom _
2001-06-07 23:49 ` Jacques Garrigue [this message]
2001-06-08 0:20 ` [Caml-list] Currying in Ocaml Mark Wotton
2001-06-08 10:13 ` Anton Moscal
[not found] ` <Pine.LNX.4.21.0106081015000.1167-100000@hons.cs.usyd.edu.a u>
2001-06-08 0:38 ` Chris Hecker
2001-06-08 8:25 ` [Caml-list] let mutable (was OCaml Speed for Block Convolutions) Ohad Rodeh
2001-06-08 15:21 ` Brian Rogoff
2001-06-08 17:30 ` Pierre Weis
2001-06-08 18:36 ` Stefan Monnier
2001-06-08 19:07 ` Pierre Weis
2001-06-08 19:30 ` Michel Quercia
2001-06-11 6:42 ` [Caml-list] should "a.(i)" be a reference? (was "let mutable") Judicaël Courant
2001-06-11 13:42 ` [Caml-list] let mutable (was OCaml Speed for Block Convolutions) Pierre Weis
2001-06-12 3:21 ` Jacques Garrigue
2001-06-12 7:43 ` Pierre Weis
2001-06-12 8:31 ` Jacques Garrigue
2001-06-12 13:15 ` Georges Brun-Cottan
2001-06-12 21:54 ` John Max Skaller
2001-06-15 9:55 ` Michael Sperber [Mr. Preprocessor]
2001-06-08 9:00 Dave Berry
2001-06-08 10:23 Dave Berry
2001-06-15 3:20 Don Syme
2001-06-15 16:05 Dave Berry
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