Re: Slow clause indexing

Sebastian Brand wrote:
> 
>
>         p([1 | PList], DataIn, DataOut) :- !,
>                 update1(PList, PListNext),
>                 ...
>                 p(PListNext, DataNext, DataOut).

The reason it is slow is that you don't get indexing
because the integer is wrapped inside the list.


>
> ...
> My questions:  Is this behaviour to be expected?  Are there
> improvements I could try?

The most straightforward would be something like:

        iterate_start(DataIn, DataOut) :-
                PList = [1,2, ... n],           %%  n is known
                p(PList, DataIn, DataOut).

	loop([], Data, Data).
	loop([I|PList], DataIn, DataOut) :-
                p(I, PList, PListNext, DataIn, DataNext),
                loop(PListNext, DataNext, DataOut).


	p(1, PList, PListNext, DataIn, DataNext) :-
		update1(PList, PListNext),
		... .
	p(2, PList, PListNext, DataIn, DataNext) :-
		update2(PList, PListNext),
		... .



-- 
 Joachim Schimpf              /             phone: +44 20 7594 8187
 IC-Parc, Imperial College   /            mailto:J.Schimpf@ic.ac.uk
 London SW7 2AZ, UK         /    http://www.icparc.ic.ac.uk/eclipse