在收件箱中免费学习函数式编程的基础 (Learn the fundamentals of functional programming — for free, in your inbox)

If you’re a software developer, you’ve probably noticed a growing trend: software applications keep getting more complicated.

如果您是软件开发人员，则可能已经注意到了一种不断增长的趋势： 软件应用程序越来越复杂。

It falls on our shoulders as developers to build, test, maintain, and scale these complex systems. To do so, we have to create well-structured code that is easy to understand, write, debug, reuse, and maintain.

当开发人员构建，测试，维护和扩展这些复杂的系统时，它就落在我们肩上。为此，我们必须创建易于理解，编写，调试，重用和维护的结构良好的代码。

But actually writing programs like this requires much more than just practice and patience.

但是实际上编写这样的程序不仅仅需要练习和耐心。

In my upcoming course, Learning Functional JavaScript the Right Way, I’ll teach you how to use functional programming to create well-structured code.

在我即将开设的课程“正确学习功能JavaScript”中 ，我将教你如何使用函数式编程来创建结构良好的代码。

But before jumping into that course (and I hope you will!), there’s an important prerequisite: building a strong foundation in the underlying principles of functional programming.

但是在进入那门课程之前(我希望您会！)，有一个重要的先决条件：在函数式编程的基本原理中打下坚实的基础。

So I’ve created a new free email course that will take you on a fun and exploratory journey into understanding some of these core principles. Let’s take a look at what the email course will cover, so you can decide how it fits into your programming education.

因此，我创建了一个新的免费电子邮件课程，它将带您进行有趣的探索性旅程，以了解其中的一些核心原则。让我们看一下电子邮件课程的内容，以便您决定如何将其纳入您的编程教育中。

什么是函数式编程？ (What is functional programming?)

So. What is “functional programming,” exactly?

所以。到底什么是“函数式编程”？

Functional programming isn’t a framework or a tool, but a way of writing code. In functional programming, we place a major emphasis on writing code using functions as “building blocks.”

函数式编程不是框架或工具，而是一种编写代码的方式。在函数式编程中，我们主要强调使用函数作为“构建块”来编写代码。

Your program is defined in terms of one main function. This main function is defined in terms of other functions, which are in turn defined in terms of still more functions — until at the bottom level the functions are just language primitives like “number” or “string.”

您的程序是根据一项主要功能定义的。主要功能是根据其他功能定义的，其他功能又定义了其他功能-直到最底层的功能都是诸如“数字”或“字符串”之类的语言原语。

If you’re reading this thinking, “Hmm, but wait? Doesn’t every language use functions to write code?” then good ?. It means you’re paying attention. You’re right — every programming language has functions. But functional programming takes it to a whole ‘nother level ?

如果您正在阅读这种想法， “嗯，还等什么？ 并非每种语言都使用函数编写代码吗？” 那好吗？这意味着您正在注意。您是对的，每种编程语言都有功能。但是函数式编程将它带到了一个全新的高度？

To understand what I mean, let’s rewind and start with the basics.Every software program has two things:

为了理解我的意思，让我们回顾一下基础知识。每个软件程序都有两件事：

Behavior
行为
Data
数据

When we’re learning about a programming paradigm — like functional programming — it’s often helpful to consider how the paradigm approaches behavior and data respectively. Behavior, for example, is handled purely using functions in functional programming. Functions are “self contained” pieces of code that accomplish a specific task. It defines a relationship between a set of possible inputs and a set of possible outputs — they usually take in data, process it, and return a result. Once a function is written, it can be used over and over and over again. Data is, well, data. In functional programming, data is immutable — meaning it can’t be changed. Rather than changing data they take in, functions in functional programming take in data as input and produce new values as output. Always. Functions and immutable data are the only two things you need to ever deal with in functional programming. To make it even simpler, functions are treated no differently than data.

当我们学习编程范例(如函数式编程)时，考虑范例如何分别处理行为和数据通常会很有帮助。例如，行为仅在函数式编程中使用函数来处理。函数是完成特定任务的“自包含”代码段。它定义了一组可能的输入和一组可能的输出之间的关系-它们通常接收数据，对其进行处理并返回结果。编写函数后，就可以一次又一次地使用它。数据就是数据。在函数式编程中，数据是不可变的，这意味着无法更改。功能编程中的功能不是更改其接收的数据，而是将数据作为输入，并产生新的值作为输出。总是。函数和不变数据是函数编程中仅需处理的两件事。为了使其更简单，对函数的对待与对数据的对待没有区别。

Put another way, functions in functional programming can be passed around as easily as data. You can refer to them from constants and variables, pass them as parameters to other functions, and return them as results from other functions. This is the most important thing to understand when approaching functional programming.

换句话说， 函数式编程中的函数可以像数据一样容易地传递。 您可以从常量和变量中引用它们，将它们作为参数传递给其他函数，并作为其他函数的结果返回。在进行函数式编程时，这是最重要的了解。

By treating functions as nothing more special than a piece of data and by only using data that is immutable, we are given a lot more freedom in terms of how we can use functions.

通过将函数视为仅比一条数据更特殊的事物，并且仅使用不可变的数据，就如何使用函数而言，我们将获得更多的自由。

Namely, it allows us to create small, independent functions that can be reused and combined together to build up increasingly complex logic. We can break any complex problem down into smaller sub-problems, solve them using functions, and finally combine them together to solve the bigger problem. Considering the ever-growing complexity of software applications, this kind of “building-block” approach makes a huge difference in keeping programs simple, modular, and understandable. This is also why developers strive to make their functions as general-purpose as possible, so that they can be combined to solve large, complex problems and reused to speed up development time for subsequent programs.

即，它使我们能够创建小的独立功能，这些功能可以重复使用并组合在一起以建立越来越复杂的逻辑。我们可以将任何复杂的问题分解为较小的子问题，使用函数解决它们，最后将它们组合在一起以解决更大的问题。 考虑到软件应用程序的日益复杂性，这种“构建块”方法在使程序保持简单，模块化和易于理解方面具有巨大的差异。这也是开发人员努力使它们的功能尽可能通用的原因，以便可以将它们组合起来解决大而复杂的问题，并可以重用它们以加快后续程序的开发时间。

Ultimately, the reason that functions are so powerful in functional programming is because the functions follow certain core tenets. Those tenets will be the subject of my email course:

最终，功能之所以在功能编程中如此强大是因为这些功能遵循某些核心原则。这些原则将成为我的电子邮件课程的主题：

Functions are pure
功能纯
Functions use immutable data
函数使用不可变数据
Functions guarantee referential transparency
功能保证参照透明
Functions are first-class entities
功能是一流的实体

After that, I’ll briefly touch on how functional programming applies these tenets to encourage us to think carefully about our data and the functions that interact with it.

之后，我将简要介绍函数式编程如何应用这些原则，以鼓励我们仔细考虑数据以及与之交互的函数。

By the end, you’ll be able to understand how this approach leads to code that is:

到最后，您将能够了解这种方法如何导致代码如下：