Version française
Home     About     Download     Resources     Contact us    
Browse thread
[Caml-list] Optional and mandatory labels with the same name in the same function ?
[ Home ] [ Index: by date | by threads ]
[ Search: ]

[ Message by date: previous | next ] [ Message in thread: previous | next ] [ Thread: previous | next ]
Date: -- (:)
From: Richard Jones <rich@a...>
Subject: Re: [Caml-list] Optional and mandatory labels with the same name in the same function ?
On Thu, Jul 15, 2004 at 11:11:53PM +0900, Jacques GARRIGUE wrote:
> Then I suppose that
>    let f x x = 33
> should also cause a warning, because this has just the same
> semantics.

It's a bit more subtle than that.  OCaml 3.07 always picks the last
argument, and ignores the others.  Thus:

# let f x x = x;;
val f : 'a -> 'b -> 'b = <fun>
# let f x x x x = x;;
val f : 'a -> 'b -> 'c -> 'd -> 'd = <fun>

But a future version might pick the first argument, or one in the
middle, or one at random.  I can't find any guarantee in the manual
that the behaviour won't change, so this might cause a bug.

Rich.

-- 
Richard Jones. http://www.annexia.org/ http://www.j-london.com/
Merjis Ltd. http://www.merjis.com/ - improving website return on investment
Perl4Caml lets you use any Perl library in your type-safe Objective
CAML programs. http://www.merjis.com/developers/perl4caml/

-------------------
To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr
Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/
Beginner's list: http://groups.yahoo.com/group/ocaml_beginners