[m-rev.] for review: add array.all_{true,false}.2

[Paul Bone]

On Mon, Jul 22, 2013 at 12:04:59PM +1000, Julien Fischer wrote:
>
> Hi Paul,
>
> On Mon, 22 Jul 2013, Paul Bone wrote:
>
>>> @@ -2612,6 +2636,40 @@ array.map_corresponding_foldl_2(P, I, N, A, B, !C, !D) :-
>>>      ).
>>>
>>> +
>>> +array.all_false(Pred, Array) :-
>>> +    do_all_false(Pred, array.min(Array), array.max(Array), Array).
>>> +
>>> +:- pred do_all_false(pred(T), int, int, array(T)).
>>> +%:- mode do_all_false(in(pred(in) is semidet), in, in, array_ui) is semidet.
>>> +:- mode do_all_false(in(pred(in) is semidet), in, in, in) is semidet.
>>> +
>>> +do_all_false(Pred, I, UB, Array) :-
>>> +    ( if I =< UB then
>>> +        Elem = Array ^ unsafe_elem(I),
>>> +        not Pred(Elem),
>>> +        do_all_false(Pred, I + 1, UB, Array)
>>> +    else
>>> +        true
>>> +    ).
>>> +
>>
>> maybe I'm bikeshedding here.  But would it not be better to implement
>> all_false in terms of all true by adding a closure?
>
> Better in what way?  (It is certainly more expensive which is probably
> why we *don't* do that for list.all_false/2.)

It avoids repitition.  But I don't know if the compiler will be able to
specalize the higher order call and then inline it.

Thanks.

-- 
Paul Bone
http://www.bone.id.au