Re: [Caml-list] duplicate labels

[Goswin von Brederlow <goswin-v-b@web.de>]

On Tue, Sep 17, 2013 at 04:49:51PM +0300, Török Edwin wrote:
> On 09/17/2013 04:09 PM, Gabriel Scherer wrote:
> > I think this is also related to
> >   http://caml.inria.fr/mantis/view.php?id=6070
> > 
> > Note that enabling warning 27 (non-suspicious unused variables) also solves this issue:
> > 
> >  % ocaml -w +27
> >         OCaml version 4.00.1
> > 
> > # let foo ~x ~x () = x;;
> > Warning 27: unused variable x.
> > val foo : x:'a -> x:'b -> unit -> 'b = <fun>
> 
> I thought that is just because I don't use x in the function, but you are right it warns even if I use x
> and I have the duplicate label:
> 
> # let foo ~x ~x () = x;;        
> Warning 27: unused variable x.
> val foo : x:'a -> x:'b -> unit -> 'b = <fun>
> 
> I think thats good enough for me now, I'll pay more attention to the unused variable warning.
> 
> Best regards,
> --Edwin

What about this code?

# let foo y ~x = 2 * x + y;;
val foo : int -> x:int -> int = <fun>
# let bar ~x = foo x;;
val bar : x:int -> x:int -> int = <fun>
# let x = 1;;
val x : int = 1
# bar ~x ~x;;
- : int = 3
# bar ~x:1 ~x:2;;
- : int = 5

Other than being confusing there doesn't seem to be anything wrong with
a duplicate label. It just requires you to apply the ~x in order.

MfG
	Goswin