gpiancastelli / prologlib Goto Github PK

For example, the following query:

?- repeat, write('hello '), fail.

does not write "hello hello hello ..." immediately. It has some kind of buffered behavior. I'm quite sure that's not what is required... need to investigate Python I/O better.

The query:

?- C = (X=Y ; X=Z), copy_term(C, C2), bagof(X, C2, S).

should give S = [_] instead of S = [_,_] as a solution. I'm not sure if the culprit is bagof/3 or copy_term/2, or some strange interaction between the two, tough.

The test for setof/3 to be found in test-builtin-predicates.SetofTest.test_with_member_predicate_7 is skipped, but really highlights some kind of bug, yet to be identified.

Given how it works, sub_atom/5 could be a first candidate for an implementation that exploits an internal generator. This would detour from the ISO specification, which seems to prescribe that all results must be computed before returning the first solution, though, so I've not made my mind up yet on it.

Parsing expressions that contains terms written in operational notation where the functor is a symbol bound to more than one operator with different arity/priority may result in the formation of a wrong term.

The most clear example involves -/2 and -/1: the simple '-'(7, 35) term get recognized as '-'(','(7, 35)) instead of '-'(7, 35), showing a conflict between '-'/1 (200) and '-'/2 (500).

For example, 0''' is not simplified to a single quote. See also test-builtin-predicates.NumberCodesTest.

The function core.unify is really long and hairy. It contains some portions of repeated code, e.g. when the Most General Unifier generated by unification between two list heads (or tails) has to update the MGU generated by the whole function. These portions could be extracted in a single function, to be implemented within core.unify, so as to shorted the already too long unification function and help clarify it a little.

See test-builtin-predicates.AtomLengthTest for an example of the problem.

The following error appears on the toplevel:

?- ;(X=1,X=2).

SyntaxError: End token expected for term: ;

\+ (as not/1) does not work because of what is probably a parser bug: the operator "scope" is much wider than the single goal, even when using parentheses!

It could be nice (and help to shape better some parts of the code) to make the parser support the Iterator protocol, implementing __next__ and __iter__, e.g. to return all the recognized terms in a for loop.

The query:

?- X = .(1, .(2, .(3, []))).

gives:

X = .(1, .(2, .(3, [])))

but it really should be X = [1,2,3].