expr

The expr function evaluates these contents when you press the = key or the Enter key .

当按下=键或Enter键时，expr函数将对这些内容进行计算。

Splits the string EXPR into a list of strings and returns that list .

分割字符串EXPR为字符串列表并且返回这个列表。

The default prefix used is EXPR .

默认的前缀是EXPR。

Forces EXPR to be interpreted in scalar context and returns the value of EXPR .

强制EXPR运行在标量上下文下并返回EXPR的值。

While I suppose we could turn around and parse these results into expr instances and interpret from there , surely another way must be available .

虽然可以将这些结果解析成expr实例并对其进行解释，但是肯定还有另外一种方法。

It uses LISPs backquote syntax to quickly construct a list from a template , filling in n and expr

的反引号语法从一个模板中快速构造出一个列表，并替换掉

However , the value of that text consists in its deep expression of the characteristics of modern criticism , which is , literary criticism is an independent creation activity and critics may expr .

但该文的价值也正好在于其深刻地体现了现代批评的特点：文学批评是独立的创作活动，批评家可以只说自己所看到的方面。

You can use the keyboard to type these in and see expr work ; and you should have enough knowledge now to modify the calculator code to add buttons that support these functions .

您可以使用键盘输入这些表达式，然后观察expr的工作，现在您已经有了足够的知识来修改该计算器代码，以添加支持这些函数的按钮。

By using Tcl / Tk 's powerful expr verb and the library of math code it can evaluate , the expression is solved and the results are placed in , well , the results variable .

通过使用Tcl/Tk的功能强大的expr动词和完成计算任务的数学代码库，实现了对表达式的计算，并且将结果保存到了results变量。

To change it to produce instances of our case class AST hierarchy ( Expr objects ), the return type of the combinators has to be changed to be Parser [ Expr ] .

要将它更改为生成case类AST层次结构的实例（Expr对象），组合子的返回类型必须更改为Parser[Expr]。

If you make that change on its own , it will fail to compile ; the three combinators know how to take in Strings but not how to produce Expr objects from what 's parsed .

如果让它自行更改，编译将会失败；这三个组合子知道如何获取String，但不知道如何根据解析的内容生成Expr对象。

Running the tests reveals that the results of the parser aren 't yet in the AST types I created earlier ( expr and its kin ), but instead in a form consisting of Lists and Strings and such .

运行测试表明，解析器的结果仍不是我前面创建的AST类型（expr和它的亲属），而是由List和String等组成的一种形式。

In the original parser , expressions like " 5 + 5 + 5 " were acceptable owing to the rep () combinator in the grammar definition for expressions ( expr ) and terms ( term ) .

在原来的解析器中，可以接受像“5+5+5”这样的表达式，因为语法中为表达式（expr）和术语（term）定义了rep（）组合子。

The documentation for the expr verb indicates that it can handle many other mathematical functions , such as asin , acos , atan , exponentials , floors , and so on .

根据expr动词的相关文档的显示，它可以处理许多其他的数学函数，如asin、acos、atan、指数、地板函数等等。