[mercury-users] foreign_type

[Peter Ross]

michael wrote:
> petdr wrote:
> > Instead you could write
> >
> > :- type constrained_foo(T) ---> constrained_foo(foo).
>
> Yes, but then the compiler thoughtfully passes everything as an
MR_Word it
> seems and I have to put back all the type casts that using foreign
type
> allowed me to remove.
>
You could write the code as follows, inlining would avoid any of the
overhead of doing it this way.

p(constrained_foo(Foo)) :-
    p_2(Foo).

:- pred p_2(foo) is semidet.

:- pragma foreign_proc(c, p_2(Foo::in), .....

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