Monitoring of errors from the top-level is not correct.

[torbjornlager]

Due to the top-level behaviour of SWI-Prolog, the following is wrong:

?- spawn(test, _, [monitor(true)]).
ERROR: Undefined procedure: test/0 (DWIM could not correct goal)
?-

This is how it should work:

?- spawn(test, _, [monitor(true)]).
true.

?- flush.
% Got down(<engine>(9,0x7fd5cdf4a080),exception(error(existence_error(procedure,test/0),context(system:once/1,_1646))))
true.

(That's how it works if we do

?- call(spawn(test, _, [monitor(true)])).
true.

instead.)

[JanWielemaker]

That is simply how the toplevel behaves: it will try to correct and find all predicates referenced from the goal. You can avoid that using : rather than 0 as meta-predicate indicator. That might make sense if we include the whole thing including the source and remote nodes. If you just use the dispatch library the current declaration is correct.

[torbjornlager]

Ok, that makes sense.

On Mon, Nov 13, 2017 at 10:01 AM, Jan Wielemaker notifications@github.com wrote:

That is simply how the toplevel behaves: it will try to correct and find all predicates referenced from the goal. You can avoid that using : rather than 0 as meta-predicate indicator. That might make sense if we include the whole thing including the source and remote nodes. If you just use the dispatch library the current declaration is correct.

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