120 lines
2.3 KiB
Plaintext
120 lines
2.3 KiB
Plaintext
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:- object(sort(_Type)).
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:- info([
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author is 'Paulo Moura',
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version is 1.0,
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date is 2000/4/22,
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comment is 'List sorting parameterized by the type of the list elements.',
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parnames is ['Type'],
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source is 'Example adopted from the SICStus Objects documentation.']).
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:- uses(list).
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:- calls(comparingp).
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:- public(sort/2).
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:- mode(sort(+list, -list), one).
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:- info(sort/2, [
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comment is 'Sorts a list in ascending order.',
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argnames is ['List', 'Sorted']]).
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:- private(partition/4).
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:- mode(partition(+list, +nonvar, -list, -list), one).
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:- info(partition/4, [
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comment is 'List partition in two sub-lists using a pivot.',
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argnames is ['List', 'Pivot', 'Lowers', 'Biggers']]).
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sort([], []).
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sort([P| L], S) :-
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partition(L, P, Small, Large),
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sort(Small, S0),
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sort(Large, S1),
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list::append(S0, [P| S1], S).
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partition([], _, [], []).
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partition([X| L1], P, Small, Large) :-
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parameter(1, Type),
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( Type::(X < P) ->
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Small = [X| Small1], Large = Large1
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; Small = Small1, Large = [X| Large1]
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),
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partition(L1, P, Small1, Large1).
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:- end_object.
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:- object(rational,
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implements(comparingp)).
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:- info([
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author is 'Paulo Moura',
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version is 1.0,
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date is 2000/4/22,
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comment is 'Implements comparison between rational numbers represented as Num/Den.']).
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N1/D1 < N2/D2 :-
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{N1*D2 < N2*D1}.
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N1/D1 =< N2/D2 :-
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{N1*D2 =< N2*D1}.
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N1/D1 > N2/D2 :-
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{N1*D2 > N2*D1}.
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N1/D1 >= N2/D2 :-
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{N1*D2 >= N2*D1}.
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N1/D1 =:= N2/D2 :-
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{N1*D2 =:= N2*D1}.
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N1/D1 =\= N2/D2 :-
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{N1*D2 =\= N2*D1}.
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:- end_object.
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:- object(colours,
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implements(comparingp)).
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:- info([
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author is 'Paulo Moura',
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version is 1.0,
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date is 2000/4/22,
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comment is 'Implements comparison between visible colors.']).
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Colour1 < Colour2 :-
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order(Colour1, N1),
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order(Colour2, N2),
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{N1 < N2}.
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Colour1 =< Colour2 :-
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order(Colour1, N1),
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order(Colour2, N2),
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{N1 =< N2}.
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Colour1 > Colour2 :-
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order(Colour1, N1),
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order(Colour2, N2),
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{N1 > N2}.
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Colour1 >= Colour2 :-
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order(Colour1, N1),
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order(Colour2, N2),
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{N1 >= N2}.
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Colour1 =:= Colour2 :-
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{Colour1 == Colour2}.
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Colour1 =\= Colour2 :-
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{Colour1 \== Colour2}.
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order(red, 1).
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order(orange, 2).
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order(yellow, 3).
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order(green, 4).
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order(blue, 5).
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order(indigo, 6).
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order(violet, 7).
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:- end_object.
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