[mercury-users] Is "High order predicates" realy high order?

[Mike Potanin]

On Fri, 22 Nov 2002, Fergus Henderson wrote:

> On 21-Nov-2002, Mike Potanin <potanin at mccme.ru> wrote:
> >
> > Do Mercury have syntax for pred it return another pred?
>
> Yes.  See the "Higher-order" chapter of the Mercury language reference manual.
Thank you!
I have not read up up to this place.

>
> > Can I write?
> > :-pred pp(pred (pred (X), pred (X))).
> > :-mode pp(pred((pred (in) is det), (pred (out) is det)) is det) is det.
>
> To make it parse correctly, you need to delete the space between "pred"
> and the immediately following "(":
Thanks yet.
>
> :- pred pp(pred(pred(X), pred(X))).
> :- mode pp(pred((pred(in) is det), (pred(out) is det)) is det) is det.
>
>

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