[Martin Meyer]

Hello Thomas,

please have a look at this code. It does not output anything neither does raise an exception (in build 7501):

Code: Select all

clauses
    run() :-
        foreach _ = std::cIterate(upperBound(unsigned)) do
            stdIo::write("*")
        end foreach.

By tracking the execution in the debugger I see, that cIterate/1-> calls fromTo/2->. It picks however the predicate domain variant (integer From, integer To) -> integer I nondeterm while it would better take (unsigned From, unsigned To) -> unsigned I nondeterm.

Many regards
Martin

[Thomas Linder Puls]

Yes, that is not good.

It is in accordance with the intension in the type system to choose the first (top most) version of cIterate that solves the "equation". and that is the second one:

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predicates
    cIterate : (integer Count) -> integer I nondeterm.
    cIterate : (unsigned Count) -> integer I nondeterm.
    cIterate : (integer Count) -> unsigned I nondeterm.
    cIterate : (unsigned Count) -> unsigned I nondeterm.

That should have resulted in an out-of-range exception when subtracting 1 in:

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clauses
    cIterate(Count) = fromTo(0, Count - 1) :-
        Count > 0.

But the std package have been equiped with a "/check:off" pragma:

Code: Select all

#options "/check:off"

And therefore the exception is not raised.

It may however make most sense to put that declatration last as it seems to be the "dangerous" one:

Code: Select all

predicates
    cIterate : (integer Count) -> integer I nondeterm.
    cIterate : (integer Count) -> unsigned I nondeterm.
    cIterate : (unsigned Count) -> unsigned I nondeterm.
    cIterate : (unsigned Count) -> integer I nondeterm.

[Martin Meyer]

Thanx Thomas,

I have put declarations to that order, now it's working fine.

Regards
Martin

[Thomas Linder Puls]