哪些函数式语言技术可以在命令式语言中使用？
哪些通常与函数式语言相关的技术或范例也可以有效地用于命令式语言？
例如：
- 在没有尾部调用优化的语言中，递归可能会出现问题，将其使用限制在少数情况下，因此其用处有限
- Map 和过滤器已经找到了进入非函数式语言的方法，即使它们具有函数式排序对他们来说，
我碰巧真的很喜欢不必担心函数式语言中的状态。 如果我特别固执，我可能会编写 C 程序而不修改变量，只将我的状态封装在传递给函数的变量和从函数返回的值中。
即使函数不是第一类值，我也可以将一个函数包装在 Java 中的一个对象中，然后将其传递到另一个方法中。 就像函数式编程一样，只是没那么有趣。
那么，对于函数式编程的老手来说，当你用命令式语言编程时，你成功应用了 FP 的哪些思想呢？
Which techniques or paradigms normally associated with functional languages can productively be used in imperative languages as well?
e.g.:
- Recursion can be problematic in languages without tail-call optimization, limiting its use to a narrow set of cases, so that's of limited usefulness
- Map and filter have found their way into non-functional languages, even though they have a functional sort of feel to them
I happen to really like not having to worry about state in functional languages. If I were particularly stubborn I might write C programs without modifying variables, only encapsulating my state in variables passed to functions and in values returned from functions.
Even though functions aren't first class values, I can wrap one in an object in Java say, and pass that into another method. Like Functional programming, just less fun.
So, for veterans of functional programming, when you program in imperative languages, what ideas from FP have you applied successfully?
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几乎全部？
如果您了解函数式语言，则可以编写由函数式风格“通知”的命令式程序。 这将使您远离副作用，并转向在任何特定点阅读程序文本足以让您真正了解程序在该点的含义的程序。
回到《黎明之时》，我们曾经担心“耦合”和“内聚”。 学习 FP 将引导您编写具有最佳（最小）耦合和高内聚性的系统。
Pretty nearly all of them?
If you understand functional languages, you can write imperative programs that are "informed" by a functional style. That will lead you away from side effects, and toward programs in which reading the program text at any particular point is sufficient to let you really know what the meaning of the program is at that point.
Back at the Dawn of Time we used to worry about "coupling" and "cohesion". Learning an FP will lead you to write systems with optimal (minimal) coupling, and high cohesion.
以下是在非 FP 语言中妨碍 FP 的因素：
Here are things that get in the way of doing FP in a non-FP language:
没有一流的函数确实会阻碍编写函数式程序，但是您可以做一些不需要它们的事情。 第一个是避免可变状态 - 尝试让大多数或所有类返回表示修改状态的新对象，而不是在内部进行更改。 例如，如果您正在使用
add操作编写链表，您可能希望从add返回新的链表，而不是修改对象。虽然这可能会降低您的程序效率（由于创建和销毁的对象数量增加），但您将能够更轻松地调试程序，因为对象的状态和操作变得更加可预测，更不用说能够嵌套函数调用更深入，因为它们有状态输入和输出。
Not having first-class functions really puts a damper on writing functional programs, but there are a few things that you can do that don't require them. The first is to eschew mutable state - try to have most or all of your classes return new objects that represent the modified state instead of making the change internally. As an example, if you were writing a linked list with an
addoperation, you would want to return the new linked list fromaddas opposed to modifying the object.While this may make your programs less efficient (due to the increased number of objects being created and destroyed) you will gain the ability to more easily debug the program because the state and operation of the objects becomes more predictable, not to mention the ability to nest function calls more deeply because they have state inputs and outputs.
我已经成功地使用了很多高阶函数，尤其是传入的函数而不是返回的函数。 返回的类型可能有点乏味，但可以模拟。
各种应用数据结构和递归函数在命令式语言中都能很好地工作。
我最怀念的事情：
几乎没有命令式语言保证优化每个尾部调用。
据我所知，没有任何命令式语言支持通过模式匹配进行案例分析。
据
I've successfully used higher-order functions a lot, especially the kind that are passed in rather than the kind that are returned. The kind that are returned can be a bit tedious but can be simulated.
All sorts of applicative data structures and recursive functions work well in imperative languages.
The things I miss the most:
Almost no imperative languages guarantee to optimize every tail call.
I know of no imperative language that supports case analysis by pattern matching.