Prolog 中的谓词列表 [英] List of predicates in Prolog

问题描述

是否可以定义一个由谓词组成的列表以及如何调用谓词.

Is it possible to define a list, that consists of predicates and how do I call the predicates.

另外，是否可以将一个谓词传递给另一个谓词(如传递原子)?

Also, is it possible to pass one predicate to another predicate (like passing atoms)?

例子:

pre1:- something.
pre2(Predicate1, List):-
    call(Predicate1),
    append([Predicate1], List, R),
    .....

推荐答案

你不能在列表中存储 谓词，但你可以存储 terms(或函子)并将术语称为目标.

You can't store predicates in a list, but you can store terms (or functors) and call terms as goals.

这是一个谓词，用于测试一个术语是否具有由函子列表描述的属性:

Here's a predicate that tests whether a term has the properties described by a list of functors:

has_properties([], _).
has_properties([P|Ps], X) :-
    Goal =.. [P, X],            % construct goal P(X)
    call(Goal),
    has_properties(Ps, X).

用法:

% is 4 a number, an integer and a foo?
?- has_properties([number, integer, foo], 4).

当然，此查询的答案取决于您对 foo/1 的定义.如果需要，请参阅我的 =.. 说明.

The answer to this query will depend on your definition of foo/1, of course. See my explanation of =.. if needed.

编辑:正如@false 在评论中报告的那样，没有必要使用=..，因为Goal =.. [P, X]，call(Goal) 可以替换成 call(P, X) 会产生同样的效果.不过，可能仍然值得学习 =..，因为您可能会在其他人的代码中遇到它.

Edit: as @false reports in the comments, it's not necessary to use =.., since Goal =.. [P, X], call(Goal) can be replaced by call(P, X) will have the same effect. It might still be worthwhile learning about =.., though, as you may encounter it in other people's code.

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