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Message-ID: <47FF3815.2040309@frisch.fr>
Date: Fri, 11 Apr 2008 12:06:13 +0200
From: Alain Frisch <alain@frisch.fr>
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To: Jon Harrop <jon@ffconsultancy.com>
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Deconstructing optional arguments
References: <200804111024.16296.jon@ffconsultancy.com>
In-Reply-To: <200804111024.16296.jon@ffconsultancy.com>
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X-Spam: no; 0.00; frisch:01 frisch:01 wrote:01 caml-list:01 alain:01 alain:01 argument:02 argument:02 let:03 let:03 pattern:04 arguments:07 label:07 optional:09 optional:09 

Jon Harrop wrote:
> Is it possible to deconstruct an optional argument as you can with a labeled 
> argument:
> 
>   let f ~p:(x,y) () = x - y
> 
> with something like:
> 
>   let f ?(p=0,0):(x,y) () = x - y

Yes, of course. The default value is attached to the pattern, not to the 
label:

let f ?p:((x,y)=(0,0)) () = x - y;;

-- Alain