Re: [Caml-list] Record field disambiguation in 4.01

[Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>]

On 2013/03/12, at 3:52, Yaron Minsky <yminsky@janestreet.com> wrote:
> On Mon, Mar 11, 2013 at 7:52 AM, Alain Frisch <alain@frisch.fr> wrote:
>> The warning tells you something useful: with that record type declaration,
>> the reference to field "y" becomes ambiguous, which means in particular that
>> (i) your code might become fragile w.r.t. reordering of type declarations,
>> (ii) the code might become harder to read (the reader might expect that
>> field "y" is typically related to a different record type in your code
>> base).  Of course, a more explicit warning message, as you suggest, would be
>> even better.

I have improved the warning (revision 13395), so that it tells you the types involved.
This should actually help in some hairy situations.

>> During the discussion on type-based disambiguation, Mark Shinwell commented
>> that most record types in JS code base are defined in nested modules (and
>> often exposed only through builder functions) to avoid label clashes.  Is
>> your example an instance where this is not the case?
> 
> It is.  If I'd turned the warning off, would it have in fact picked
> the more recent definition?

Yes, the new strategy is fully backward-compatible.
It just accepts more programs, and there are many new warnings so
that you can tune it to your taste. Using all of them is probably self-defeating,
as for instance warning 42 warns you when something has been accepted
that was not accepted before.

	Jacques