检查序言列表元素的关系 [英] Checking a relation of a prolog list element

问题描述

让我说有一段恋情

Happy(james)
Happy(harry)
unhappy(Tom)
unhappy(Ben)
unhappy(Dick)

然后是人员列表

[Ben, James, Harry, Tom, Dick]

如何迭代列表并检查每个列表元素的布尔值是否满意?

How can I iterate the list and check the boolean of each list element as to whether they are happy or not?

推荐答案

首先，在Prolog中，如果单词以大写字母开头，则表示它是一个变量.因此，您应该注意这一点.

Well, first of all, in Prolog, if a word starts with a capital letter, it means that it is a variable. So you should be careful with that.

这是更正后的我的数据库:

This is my database after the correction:

happy(james).
happy(harry).
unhappy(tom).
unhappy(ben).
unhappy(dick).

并且我添加了一个递归规则，该规则可以帮助我查看谁在给定列表中感到高兴和不高兴:

and I added a recursive rule that helps me see who is happy and who is not from a given list:

emotion([]).
emotion([H|T]):- happy(H),emotion(T),
                 write(H),write(' is happy.'),
                 nl;
                 unhappy(H),emotion(T),
                 write(H),write(' is unhappy.'),
                 nl.

这是结果:

4 ?- emotion([ben, james, harry, tom, dick]).
dick is unhappy.
tom is unhappy.
harry is happy.
james is happy.
ben is unhappy.
true.

这篇关于检查序言列表元素的关系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！