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From: Jon Harrop <jon@ffconsultancy.com>
Organization: Flying Frog Consultancy Ltd.
To: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] evaluation order
Date: Sun, 14 Jun 2009 20:40:47 +0100
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X-Spam: no; 0.00; christophe:01 raffalli:01 ocaml-:01 bytecode:01 nativecode:01 decr:01 ocamlc:01 ocamlopt:01 bug:01 2009:98 frog:98 wrote:01 caml-list:01 arithmetic:01 undefined:01 

On Sunday 14 June 2009 17:36:39 Christophe Raffalli wrote:
> Hello,
>
> In OCaml-3.11.1 (I did not try other version),
> the following code print 0 when compiled in bytecode and 1 in nativecode
> for obvious reason of different evaluation order in the pair ...
>
>
> let ptr = ref 0
> let fn b =
>   if b then incr ptr else decr ptr
> let c = fn true, !ptr
> let _ = print_int (snd c); print_newline ()
>
> Is any difference between ocamlc and ocamlopt a bug ?

Not at all, no. They are expected to have different behaviour with respect to 
floating point arithmetic. In this case, they have chosen to evaluate 
subexpressions in a different order, which is fine because the order of 
evaluation is officially undefined.

-- 
Dr Jon Harrop, Flying Frog Consultancy Ltd.
http://www.ffconsultancy.com/?e