Różnice między wybraną wersją a wersją aktualną.
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pl:prolog:pllib:rule_interpreter [2019/06/27 15:50] |
pl:prolog:pllib:rule_interpreter [2019/06/27 15:50] (aktualna) |
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| + | ====== Rule interpreter ====== | ||
| + | {{tag>interpreter rules}} | ||
| + | ===== Description ===== | ||
| + | A two-level rule interpreter carrying rules | ||
| + | |||
| + | **Source**: The Art of Prolog | ||
| + | ===== Download ===== | ||
| + | Program source code: {{rule_interpreter.pl}} | ||
| + | ===== Listing ===== | ||
| + | <code prolog> | ||
| + | /* | ||
| + | monitor(Goal) :- | ||
| + | Succeeds if a result of yes is returned from solving Goal | ||
| + | at the solve level, or when the end of the computation is reached. | ||
| + | */ | ||
| + | :- op(40,xfy,&). | ||
| + | :- op(30,xf,is_true). | ||
| + | |||
| + | monitor(Goal) :- solve(Goal,Result,[ ]), filter(Result). | ||
| + | monitor(Goal). | ||
| + | |||
| + | filter(yes). | ||
| + | % filter(no) :- fail. | ||
| + | |||
| + | /* | ||
| + | solve(Goal,Result,Rules) :- | ||
| + | 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. | ||
| + | Rules is the current list of rules that have been used. | ||
| + | */ | ||
| + | solve(A,yes,Rules) :- fact(A). | ||
| + | solve(A,Result,Rules) :- | ||
| + | rule(A,B,Name), RulesB = [NamejRules], | ||
| + | solve_body(B,Result,RulesB). | ||
| + | solve(A,no,Rules). | ||
| + | |||
| + | solve_body(A&B,Result,Rules) :- | ||
| + | solve_body(A,ResultA,Rules), | ||
| + | solve_and(ResultA,B,Result,Rules). | ||
| + | solve_body(A is_true,Result,Rules) :- solve(A,Result,Rules). | ||
| + | |||
| + | solve_and(no,A,no,Rules). | ||
| + | solve_and(yes,B,Result,Rules) :- solve(B,Result,Rules). | ||
| + | |||
| + | % Program 17.20: A two-level rule interpreter carrying rules | ||
| + | </code> | ||
| + | ===== Comments ===== | ||
