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pl:prolog:pllib:interactive_interpreter [2019/06/27 15:50] (aktualna)
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 +====== Interactive interpreter ======
 +{{tag>​interpreter interactive}}
 +===== Description =====
 +An interactive rule interpreter
 +
 +**Source**: ​ The Art of Prolog
 +===== Download =====
 +Program source code: {{interactive_interpreter.pl}}
 +===== Listing =====
 +<code prolog>
 +/*
 +    solve(Goal,​Result) :-
 +       Given a set of rules of the form rule(A,​B,​Name),​ Goal has
 +       ​Result yes if it follows from the rules and no if it does not.
 +       The user is prompted for missing information.
 +*/
 +:- op(40,​xfy,&​).
 +:- op(30,​xf,​is_true).
 +:-  op( 900, fy, not).
 +
 +    solve(A,​yes) :-  fact(A).
 +    solve(A,​Result) :-  rule(A,​B,​Name),​ solve_body(B,​Result).
 +    solve(A,​Result) :-  askable(A), solve_askable(A,​Result).
 +    solve(A,​no).
 +
 +    solve_body(A&​B,​Result) :-
 +       ​solve_body(A,​ResultA),​ solve_and(ResultA,​B,​Result).
 +    solve_body(A is_true,​Result) :-  solve(A,​Result).
 +
 +    solve_and(no,​A,​no).
 +    solve_and(yes,​B,​Result) :-  solve(B,​Result).
 +
 +    solve_askable(A,​Result) :-
 +       not known(A), ask(A,​Response),​ respond(Response,​A,​Result).
 +
 +%    The following predicates facilitate interaction with the user.
 +
 +    ask(A,​Response) :-  display_query(A),​ read(Response).
 +
 +    respond(yes,​A,​yes) :-  assert(known_to_be_true(A)).
 +    respond(no,​A,​no) :-  assert(known_to_be_false(A)).
 +
 +    known(A) :-  known_to_be_true(A).
 +    known(A) :-  known_to_be_false(A).
 +
 +    display_query(A) :-  write(A), write('? ​ ').
 +
 +%    Program 17.19: An interactive rule interpreter
 +</​code>​
 +===== Comments =====
  
pl/prolog/pllib/interactive_interpreter.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)
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