33 lines
846 B
Perl
33 lines
846 B
Perl
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% taken from http://stackoverflow.com/questions/12272888/default-prolog-predicate-sort
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/* File: order_by.pl
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Author: Carlo,,,
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Created: Sep 5 2012
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Purpose: sort fact
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*/
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:- module(order_by,
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[order_by/2
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]).
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:- use_module(library(apply_macros)).
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order_by(PredicateIndicator, Argument) :-
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( PredicateIndicator = Module:Functor/Arity
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; PredicateIndicator = Functor/Arity, Module = user
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),
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length(EmptyArgs, Arity),
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P =.. [Functor|EmptyArgs],
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findall(P, retract(Module:P), L),
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predsort(by_arg(Argument), L, S),
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maplist(assert_in_module(Module), S).
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assert_in_module(Module, P) :-
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assertz(Module:P).
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by_arg(Argument, Delta, E1, E2) :-
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arg(Argument, E1, A1),
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arg(Argument, E2, A2),
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( A1 @< A2
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-> Delta = <
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; Delta = >
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).
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