--- pl:prolog:pllib:tracer [2019/06/27 15:50]
+++ pl:prolog:pllib:tracer [2019/06/27 15:50] (aktualna)
@@ Linia 1: / Linia 1: @@
+====== Tracer ======
+{{tag>tracers}}
+===== Description =====
+A tracer for Prolog
+**Source**:  The Art of Prolog
+===== Download =====
+Program source code: {{tracer.pl}}
+===== Listing =====
+<code prolog>
+/*
+  solve_trace(Goal) :-
+	Goal is true given the pure Prolog program defined by
+	clause/2. The program traces the proof by side effects.
+*/
+solve_trace(Goal) :-
+	solve_trace(Goal,0).
+     solve_trace(true,Depth) :- !.
+     solve_trace((A,B),Depth) :-  !,
+        solve_trace(A,Depth), solve_trace(B,Depth).
+     solve_trace(A,Depth) :-
+	builtin(A), !, A, display(A,Depth), nl.
+     solve_trace(A,Depth) :-
+        clause(A,B),
+	display(A,Depth), nl,
+	Depth1 is Depth + 1,
+	solve_trace(B,Depth1).
+     display(A,Depth) :-  Spacing is 3*Depth, put_spaces(Spacing), write(A).
+     	put_spaces(N) :- between(1,N,I), put_char(' '), fail.
+	put_spaces(N).
+     between(I,J,I) :- I =< J.
+     between(I,J,K) :- I < J, I1 is I + 1, between(I1,J,K).
+%	Program 17.7	A tracer for Prolog
+</code>
+===== Comments =====

pl/prolog/pllib/tracer.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)

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