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 — pl:prolog:pllib:rule_interpreter_4 [2019/06/27 15:50] (aktualna) Linia 1: Linia 1: + ====== Rule interpreter 4 ====== + {{tag>​rules interpreter}} + ===== Description ===== + Specializing a rule interpreter + + **Source**: ​ The Art of Prolog + ===== Download ===== + Program source code: {{rule_interpreter_4.pl}} + ===== Listing ===== + + /* + Rule interpreter for counting reductions + */ + + :- op(40,​xfy,&​). + :- op(30,​xf,​is_true). + + solve(A,1) :-  fact(A). + solve(A,N) :-  rule(A,​B,​Name),​ solve_body(B,​NB),​ N is NB+1. + + solve_body(A&​B,​N) :- + ​solve_body(A,​NA),​ solve_body(B,​NB),​ N is NA+NB. + solve_body(A is_true,N) :-  solve(A,N). + + %        Sample rule base + + rule(oven(Dish,​top),​pastry(Dish) is_true + & size(Dish,​small) is_true,​place1). + rule(oven(Dish,​middle),​pastry(Dish) is_true + & size(Dish,​big) is_true,​place2). + rule(oven(Dish,​middle),​main_meal(Dish) is_true,​place3). + rule(oven(Dish,​bottom),​slow_cooker(Dish) is_true,​place4). + rule(pastry(Dish),​type(Dish,​cake) is_true,​pastry1). + rule(pastry(Dish),​type(Dish,​bread) is_true,​pastry2). + rule(main_meal(Dish),​type(Dish,​meat) is_true,​main_meal). + rule(slow_cooker(Dish),​type(Dish,​milk_pudding) + ​is_true,​slow_cooker). + + should_fold(solve(oven(D,​P),​N),​oven(D,​P,​N)). + should_fold(solve(pastry(D),​N),​pastry(D,​N)). + should_fold(solve(main_meal(D),​N),​main_meal(D,​N)). + should_fold(solve(slow_cooker(D),​N),​slow_cooker(D,​N)). + should_fold(solve(type(D,​P),​N),​type(D,​P,​N)). + should_fold(solve(size(D,​P),​N),​size(D,​P,​N)). + + should_unfold(solve_body(G,​N)). + should_unfold(rule(A,​B,​Name)). + + program(rule_interpreter,​[(solve(A1,​1) :-  fact(A1)), + ​(solve(A2,​N) :-  rule(A2,​B,​Name),​ solve_body(B,​NB),​ N is NB+1)]). + + %        Program 18.5: Specializing a rule interpreter + ​ + ===== Comments =====
pl/prolog/pllib/rule_interpreter_4.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)