[m-dev.] help with polymorphic modes

[Peter Wang]

On Tue, 2 Sep 2014 15:19:44 +1000, Peter Wang <novalazy at gmail.com> wrote:
> Hi,
>
> Just to make sure, this is mode incorrect, yes?
>
>     :- pred p(pred(T), T).
>     :- mode p(pred(in(I =< ground)) is det, in) is det.
>
>     p(P, X) :- P(X).

That doesn't make sense.  Then what about this?

    :- type fruit --->  apple ; orange.
    :- inst apple --->  apple.

    :- pred apple_only(fruit).
    :- mode apple_only(in(I =< apple)) is det.

    apple_only(_).

    test :- p(apple_only, orange).

Peter