[m-dev.] for discussion: proposed additions to FFI

Julien Fischer juliensf at csse.unimelb.edu.au
Tue Jun 24 15:00:05 AEST 2008

On Tue, 24 Jun 2008, Ralph Becket wrote:

> Julien Fischer, Tuesday, 24 June 2008:
>> On Tue, 24 Jun 2008, Ralph Becket wrote:
>>> Julien Fischer, Monday, 23 June 2008:
>>>> This proposal extends the FFI with three new pragmas that allow for the
>>>> construction, deconstruction and testing of individual discriminated union
>>>> data constructors in foreign language code.
>>> I think this is a reasonable idea, although I wonder whether in
>>> practice you're almost always going to want all three operations
>>> (cons/decons/test), which might mean having a single pragma to generate
>>> all three would be better.
>> How about listing the desired operations in a single pragma, something
>> like:
>> 	:- pragma foreign_export_du_op("C", maybe, yes,
>> 		[test("TEST_yes"), cons("MAKE_yes"),
>> 		decons("UNAKE_yes")]).
> I'll raise you a level:
> 	:- pragma foreign_export_du_op("C", maybe,
> 		[yes - [test("TEST_yes"), cons("MAKE_yes"),
> 			decons("UNAKE_yes")],
> 		 no - [test("TEST_no")]]).


I'm not crazy about the nested lists, but it looks good aside from that.
Mark was saying that it might also be useful to have access to
individual fields as well.

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