什么是Prolog运算符"^"(“插入符")? [英] What is the Prolog operator `^` ("caret")?

问题描述

什么是Prolog运算符^?

What is the Prolog operator ^ ?

查看 Prolog内置指令op 给出了内置运算符的列表.

Looking at The Prolog Built-in Directive op gives a list of the built-in operators.

我知道

• **是求幂
• /\是或

• ** is exponentiation
• /\ is or

但是^是什么?

当前三个答案中的每一个都是有价值的，我学到了一些东西:

Each of the three current answers are of value and I learned something:

• 这本书的罗伊
• 示例错误
• 我接受CapelliC的回答，因为它清楚表明^/2具有多种含义
  视情况而定，这立即消除了我的困惑.

• Roy for the book
• false for the examples
• I accepted the answer by CapelliC because it made clear that ^/2 has multiple meanings
  depending on context which instantly cleared up my confusion.

推荐答案

在Prolog中，大多数符号可以在语法级别未解释"使用，尤其是在op/3声明之后，任何原子都可以用作操作员.然后，您可以使用^/2作为域特定语言(DSL)的函数构造函数，并使用规则中指定的语义.

In Prolog, most symbols can be used 'uninterpreted', at syntactic level, in particular after an op/3 declaration, any atom can be used as operator. Then you can use, for instance, ^/2 as a function constructor for a domain specific language (a DSL), with a semantic specified from your rules.

是SWI-Prolog(或更常见的是ISO Prolog)，current_op/3为您提供有关已声明的运算符的信息:

Is SWI-Prolog (or more generally in ISO Prolog), current_op/3 gives you information about declared operators:

?- current_op(X,Y,^).
X = 200,
Y = xfy. 

也就是说，在装饰2 ^nd 参数时，任何实现setof/3的Prolog都应将^/2解释为量化说明符.同样，当任何实现is/2的Prolog出现在is/2表达式的右侧时，都应该将^/2解释为幂.

That said, any Prolog implementing setof/3 is expected to interpret ^/2 as a quantification specifier, when put to decorate the 2^nd argument. As well, any Prolog implementing is/2 is expected to interpret ^/2 as exponentiation, when occurring on the right side of the is/2 expression.

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