在 Prolog 中获取谓词的所有解决方案 [英] Getting all the solutions to a predicate in Prolog

问题描述

我正在 Prolog 中编写文本冒险游戏，并且正在打印房间出口.我有这样的代码:

I'm writing a text adventure game in Prolog, and I am printing out room exits. I have code that does:

exits_from(Room) :-
  connected(Room, X),
  write(X), write('  ').

connected/2 在哪里:

where connected/2 is:

connected(X, Y) :- path(X, Y).
connected(X, Y) :- path(Y, X).

路径是:

path(room, hallway).
path(hallway, foyer).

等等.

当我打印房间的出口时，它得到第一个，然后需要一个 ';'说我想要另一个解决方案.无论如何要强制谓词完全计算结果，以便玩家不必继续要求更多退出?

When I am printing the exits for a room though, it gets the first, then wants a ';' to say that I want another solution. Is there anyway to force a predicate to compute the result entirely, so that the player wouldn't have to keep asking for more exits?

推荐答案

一种方法是做类似的事情

one way is to do something like

print_all_solutions :-
  solution(Sol),
  write(Sol),
  fail. % this causes backtracking
print_all_solutions. % succed

另一种是使用特殊谓词forall，如下所示:

another is to use special predicate forall, like follows:

forall(solution(Sol), write(Sol))

这篇关于在 Prolog 中获取谓词的所有解决方案的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！