如何在 prolog 中打印所有数据库事实 [英] how can I print all database facts in prolog

问题描述

我在 prolog 中有一个数据库，我想做的就是枚举它的元素并一一打印.这怎么办?

I have a database in prolog, all I want to do is enuamrate through its element and print one by one. How can this be done?

fact(is(mike,asthmatic)).
fact(has(andy,highPressure)).
fact(is(mike,smoker)).

我写了这个，它工作正常，但它从数据库中删除了元素，所以我想在不删除的情况下访问它们.

I have written this, which works ok but it removes elements from the database, so I want to access them without removing.

print:- 
  retract(factA(P)),
    write(factA(P)),nl,
    fail.
  print.

推荐答案

您也可以考虑使用 forall/2 谓词:

You might also consider using forall/2 predicate:

print:-
 forall(fact(P), writeln(P)).

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