/* NOTE: directives are predicates to run at load time :- Body. */ % include database :- include('db.pl'). % directive to include file % :- include('filename.pl'). :- X = green, color(X), format('~w is a color.', [X]). % green is a color. :- X = boat, color(X), format('~w is a color.', [X]). % Goal (directive) failed: ... :- X = sweden, person(Y, nationality(X, _)), format('~w is from ~w.', [Y, X]). % michael is from sweden. :- X = michael, friend_with(X, Y). % michael is friend with adam