简单地说，方法是在类中声明的函数。
函数索引是一种强大的性能调优工具。
Functional indexes can be a powerful performance tuning tool.
Haskell允许把函数当成数据。
记住，变量可以保存函数！
此外，递归函数也增强了语言的表达能力。
In addition, recursive functions add significant expressive power to the language.
选择的名称应当能很好地提示函数的功能。
The name you choose should provide a good hint about what the function does.
在新方法中，函数名清楚地表明了要做什么。
In the new way, the name of the function explains your intention.
你顺带还会学到一星半点函数式编程的知识。
You may also learn a thing or two about functional programming.
这是函数式编程语言中常见的一个强大特性。
This is a powerful feature common in functional programming languages.
XSLT是一种函数式语言而不是过程性语言。
不过事实证明函数型语言非常适合于并行编程。
But functional languages turn out to be very well suited to parallel programming.
在数学中，函数把每个输入映射到一个特定的输出。
In mathematics, a function maps each input to a specific output.
可以在简单的SQL查询中轻松地调用此函数。
This function can be easily invoked from a simple SQL query.
总之，测试函数可以极大地增强编写测试的简便性。
Above all, test functions vastly enhance what might be called the writability of tests.
后续内容还会对闭包与高阶函数做一些有趣的对比。
I'll also circle back to some interesting comparisons between closures and higher-order functions in a later installment.
此函数易于使用，支持GET和POST请求类型。
This function is easy to use, and it supports both the GET and POST request types.
可以看出这些函数非常简单直观，很容易理解和掌握。
You can see that these functions are fairly straightforward, and you can pick them up in no time.
在过去的几年中，人们对函数式编程语言的兴趣高涨。
In the past couple of years, interest in functional programming has skyrocketed.
函数式编程不只是一组工具或者语言，更是一种心态。
Functional programming is more a mindset than a particular set of tools or languages.
这些函数有助于促进代码重用，简化查询的开发和维护。
Such functions encourage code reuse and simplify the development and maintenance of queries.
在下一篇文章中，您将学会如何高效率地使用变量和函数。
In the next installment, you will learn how to employ variables and functions efficiently.
编写创建空数据库的函数是演示小型单一功能例程的好例子。
Coding a function to create an empty database is a good example of a small, single-function routine.
我将额外向您展示如何用php中的变量和函数变一些戏法。
As a bonus, I will show you how to do some magic with variables and functions in PHP.
在编写php时，这个函数是一个简单但很有帮助的调试工具。
This function is a rudimentary, yet helpful, debugging tool when working with PHP.
使用大量参数的复杂函数几乎都能被拆分成多个更简单的函数。
Complex functions that take many arguments can almost always be broken down to simpler ones.
最重要的是，您创建了一些通用函数用于处理任意数量的竞争者。
Most significantly, you created generic functions that can handle any number of contestants.
如果没有找到需要的函数，可以尝试在样式表中编写自己的函数。
If you don't find what you need, then learn to write your own function in the stylesheet.
在这种情况下，在使用之处声明此函数会有助于提高代码的可读性。
In such a case, declaring the function at its place of use lets you improve the readability of your code.
如果你发现自己总是过分注释，请先把函数命名和变量命名处理好。
If you are over-commenting, you're probably naming your functions and variables poorly.
函数式编程的核心是函数，就像面向对象语言的主要抽象方法是类。
At the core of functional programming is the function, just as classes are the primary abstraction in object-oriented languages.
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