> For the complete documentation index, see [llms.txt](https://3440217568.gitbook.io/rxswift/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://3440217568.gitbook.io/rxswift/think_reactive/functional_reactive_progaramming.md).

# 3.2 函数式编程 -> 函数响应式编程

现在大家已经了解我们是如何运用**函数式编程**来操作序列的。其实我们可以把这种操作序列的方式再升华一下。例如，你可以把一个按钮的点击事件看作是一个序列：

![](/files/-MWlwMeLdLQQVOyapO-G)

```swift
// 假设用户在进入页面到离开页面期间，总共点击按钮 3 次

// 按钮点击序列
let taps: Array<Void> = [(), (), ()]

// 每次点击后弹出提示框
taps.forEach { showAlert() }
```

这样处理点击事件是非常理想的，但是问题是这个序列里面的元素（点击事件）是异步产生的，传统序列是无法描叙这种元素异步产生的情况。为了解决这个问题，于是就产生了**可监听序列**`Observable<Element>`。它也是一个序列，只不过这个序列里面的元素可以是同步产生的，也可以是异步产生的:

![](/files/-MWlwMeM_wGWn7XZ_PUl)

```swift
// 按钮点击序列
let taps: Observable<Void> = button.rx.tap.asObservable()

// 每次点击后弹出提示框
taps.subscribe(onNext: { showAlert() })
```

这里 `taps` 就是按钮点击事件的序列。然后我们通过弹出提示框，来对每一次点击事件做出响应。这种编程方式叫做**响应式编程**。我们结合**函数式编程**以及**响应式编程**就得到了**函数响应式编程**：

![](/files/-MWlwMeNBt4lbkonXtpx)

```swift
passwordOutlet.rx.text.orEmpty
    .map { $0.characters.count >= minimalPasswordLength }
    .bind(to: passwordValidOutlet.rx.isHidden)
    .disposed(by: disposeBag)
```

我们通过不同的构建函数，来创建所需要的数据序列。最后通过适当的方式来响应这个序列。这就是**函数响应式编程**。


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