Asserting a fact when triggering a rule

	Hi, there,

	I'm new to SWI Prolog. I'm using it through pySWIP, a bridge between SWI Prolog and Python.

	I need to assert an extra fact when a given rule is triggered. I know how to do this in Pyke, but, I can't figure it out in SWI Prolog.

	So, an example would be:

	person( X ) :-
				human( X ).

	So, every human is also a person. But say I want to assert that it is also a mammal. I can do it repeating the rule:

	person( X ) :-
				human( X ).
	mammal( X ) :-
				human( X ).

	However, I've been trying to accomplish this in swipl, and it seems that the second rule is not triggered unless a query asks for it.

	I wonder whether it would be possible to assert both facts at the same time, something like:

	person(X) :-
				human(X),
				if_triggered(assert(mammal(X))).


	Thanks in advance,

-- 
Baltasar García Perez-Schofield ([email protected])
Dpt. Informática, Universidad de Vigo, España
http://webs.uvigo.es/jbgarcia/