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yap-6.3/Logtalk/examples/birds/expert.lgt

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:- object(expert,
imports(protected::descriptors)).
:- info([
author is 'Paulo Moura',
version is 1.0,
date is 2000/2/18,
comment is 'Expert system for bird identification.',
source is 'Example adopted from an Amzi! Inc Prolog book.']).
:- public(identify/0).
:- mode(identify, one).
:- info(identify/0,
[comment is 'Starts a bird identification session.']).
:- private(known_/3).
:- dynamic(known_/3).
:- mode(known_(?nonvar, ?nonvar, ?nonvar), zero_or_more).
:- info(known_/3, [
comment is 'Table of already known facts.',
argnames is ['Answer', 'Attribute', 'Value']]).
identify :-
::retractall(known_(_, _, _)),
write('Bird identification expert system'), nl, nl,
forall(
(order::leaf(Bird), check(Bird)),
(nl, write('Possible identification : '), write(Bird), nl)),
nl, write('No (more) candidates found.').
check(Bird) :-
forall(
(::descriptor(Functor/Arity),
functor(Predicate, Functor, Arity),
Bird::Predicate),
call(Predicate)).
bill(X):-
ask(bill, X).
cheek(X):-
ask(cheek, X).
color(X):-
ask(color, X).
eats(X):-
ask(eats, X).
feed(X):-
ask(feed,X).
feet(X):-
ask(feet, X).
flight(X):-
menuask(flight, X, [ponderous, powerful, agile, flap_glide, other]).
flight_profile(X):-
menuask(flight_profile, X, [flat, v_shaped, other]).
head(X):-
ask(head,X).
live(X) :-
ask(live, X).
neck(X):-
ask(neck, X).
nostrils(X):-
ask(nostrils, X).
size(X):-
menuask(size, X, [large, plump, medium, small]).
tail(X):-
menuask(tail, X, [narrow_at_tip, forked, long_rusty, square, other]).
throat(X):-
ask(throat, X).
voice(X):-
ask(voice,X).
wings(X):-
ask(wings, X).
ask(Attribute,Value):-
::known_(yes, Attribute, Value),
!.
ask(Attribute,Value):-
::known_(_, Attribute, Value),
!, fail.
ask(Attribute,_):-
::known_(yes, Attribute, _),
!, fail.
ask(Attribute, Value):-
write(Attribute:Value),
write('? (yes or no): '),
read(Answer),
::asserta(known_(Answer, Attribute, Value)),
Answer = yes.
menuask(Attribute,Value, _):-
::known_(yes, Attribute, Value),
!.
menuask(Attribute, _, _):-
::known_(yes, Attribute, _),
!, fail.
menuask(Attribute, AskValue, Menu):-
nl, write('What is the value for '), write(Attribute), write('?'), nl,
display_menu(Menu),
write('Enter the number of choice> '),
read(Num),nl,
pick_menu(Num, AnswerValue, Menu),
::asserta(known_(yes,Attribute,AnswerValue)),
AskValue = AnswerValue.
display_menu(Menu):-
display_menu(Menu, 1).
display_menu([], _).
display_menu([Item| Rest], N):-
write(N), write(' : '), write(Item), nl,
NN is N + 1,
display_menu(Rest, NN).
pick_menu(N, Val, Menu):-
integer(N),
pic_menu(1, N, Val, Menu), !.
pick_menu(Val, Val, _).
pic_menu(_, _, none_of_the_above, []).
pic_menu(N, N, Item, [Item| _]).
pic_menu(Ctr, N, Val, [_| Rest]):-
NextCtr is Ctr + 1,
pic_menu(NextCtr, N, Val, Rest).
:- end_object.