Top down query has incorrect/differing behavior

[ntbertram]

Hi,

Thanks for this helpful library!
I seem to have found an instance where querying a top down database gives an incorrect answer.

Here's the program:

foo(a1, a3).
foo(a2, a3).
fooAlso(X, Y) :- foo(X, Y).
bar(a1, a2).
baz(a3, X) :- fooAlso(X, a3), fooAlso(Y, a3), bar(X, Y).
result(a3, X) :- fooAlso(X, a3), ~baz(a3, X).

Querying result(a3, X) returns [result(a3, a2); result(a3, a1)], however, result(a3, a1) should not be in query output. On the other hand, if you query instead result(a3, a1), the output is empty, which is the expected behavior.

Interestingly, if you replace fooAlso(Y, a3) with foo(Y, a3) in the baz clause, querying result(a3, X) returns the desired output [result(a3,a2)].

Here's a zip file of a dune project containing this example, if that's helpful.
bug.zip

Can you confirm this is a bug? Or maybe I'm not using this library properly?

Thanks!

[c-cube]

Hi! Sorry, it took me a while to look at this. Would you try #14 ?