我相信过程式/函数式/目标式编程是关于如何处理问题的。

The first style would plan everything in to steps, and solves the problem by implementing one step (a procedure) at a time. On the other hand, functional programming would emphasize the divide-and-conquer approach, where the problem is divided into sub-problem, then each sub-problem is solved (creating a function to solve that sub problem) and the results are combined to create the answer for the whole problem. Lastly, Objective programming would mimic the real world by create a mini-world inside the computer with many objects, each of which has a (somewhat) unique characteristics, and interacts with others. From those interactions the result would emerge.

每种编程风格都有自己的优点和缺点。因此，做一些诸如“纯编程”(即纯粹的程序设计——顺便说一下，没有人会这样做，这有点奇怪——或纯粹的函数式或纯粹的目标)是非常困难的，如果不是不可能的话，除了一些专门设计来展示编程风格优势的基本问题(因此，我们称那些喜欢纯粹的人为“weenie”:D)。

Then, from those styles, we have programming languages that is designed to optimized for some each style. For example, Assembly is all about procedural. Okay, most early languages are procedural, not only Asm, like C, Pascal, (and Fortran, I heard). Then, we have all famous Java in objective school (Actually, Java and C# is also in a class called "money-oriented," but that is subject for another discussion). Also objective is Smalltalk. In functional school, we would have "nearly functional" (some considered them to be impure) Lisp family and ML family and many "purely functional" Haskell, Erlang, etc. By the way, there are many general languages such as Perl, Python, Ruby.

我相信过程式/函数式/目标式编程是关于如何处理问题的。

The first style would plan everything in to steps, and solves the problem by implementing one step (a procedure) at a time. On the other hand, functional programming would emphasize the divide-and-conquer approach, where the problem is divided into sub-problem, then each sub-problem is solved (creating a function to solve that sub problem) and the results are combined to create the answer for the whole problem. Lastly, Objective programming would mimic the real world by create a mini-world inside the computer with many objects, each of which has a (somewhat) unique characteristics, and interacts with others. From those interactions the result would emerge.

每种编程风格都有自己的优点和缺点。因此，做一些诸如“纯编程”(即纯粹的程序设计——顺便说一下，没有人会这样做，这有点奇怪——或纯粹的函数式或纯粹的目标)是非常困难的，如果不是不可能的话，除了一些专门设计来展示编程风格优势的基本问题(因此，我们称那些喜欢纯粹的人为“weenie”:D)。

Then, from those styles, we have programming languages that is designed to optimized for some each style. For example, Assembly is all about procedural. Okay, most early languages are procedural, not only Asm, like C, Pascal, (and Fortran, I heard). Then, we have all famous Java in objective school (Actually, Java and C# is also in a class called "money-oriented," but that is subject for another discussion). Also objective is Smalltalk. In functional school, we would have "nearly functional" (some considered them to be impure) Lisp family and ML family and many "purely functional" Haskell, Erlang, etc. By the way, there are many general languages such as Perl, Python, Ruby.

进一步阐述康拉德的评论:

因此，纯函数式程序总是对输入产生相同的值，求值的顺序没有很好的定义;

因此，函数式代码通常更容易并行化。由于函数(通常)没有副作用，并且它们(通常)只是作用于它们的参数，因此许多并发问题都消失了。

当您需要能够证明您的代码是正确的时，也可以使用函数式编程。这在过程式编程中要困难得多(在函数式编程中不容易，但仍然容易)。

免责声明:我已经很多年没有使用函数式编程了，直到最近才开始重新研究它，所以我在这里可能不完全正确。：）

要理解其中的区别，需要理解过程式编程和函数式编程的“教父”范式都是命令式编程。

基本上，过程式编程只是构造命令式程序的一种方式，其中主要的抽象方法是“过程”。(或某些编程语言中的“函数”)。甚至面向对象编程也只是构造命令式程序的另一种方式，其中状态被封装在对象中，成为一个具有“当前状态”的对象，加上这个对象有一组函数、方法和其他东西，可以让程序员操作或更新状态。

现在，关于函数式编程，其方法的要点是它确定要取什么值，以及应该如何传递这些值。(因此没有状态，也没有可变数据，因为它将函数作为第一类值，并将它们作为参数传递给其他函数)。

PS:理解所使用的每一种编程范式应该能澄清它们之间的差异。

PSS:归根结底，编程范式只是解决问题的不同方法。

PSS: quora上的这个答案有一个很好的解释。

@Creighton:

在Haskell中有一个叫做product的库函数:

prouduct list = foldr 1 (*) list

或者仅仅是:

product = foldr 1 (*)

惯用语的阶乘

fac n = foldr 1 (*)  [1..n]

很简单

fac n = product [1..n]

我从来没有在其他地方看到过这样的定义，但我认为这很好地总结了这里给出的差异:

函数式编程主要关注表达式

过程式编程主要关注语句

表达式有值。函数式程序是一个表达式，其值是由计算机执行的一系列指令。

语句没有值，而是修改一些概念机器的状态。

在纯函数式语言中，没有语句，也就是说没有办法操纵状态(它们可能仍然有一个名为“语句”的语法结构，但除非它操纵状态，否则我不会在这种意义上称其为语句)。在纯程序语言中，没有表达式，一切都是操纵机器状态的指令。

Haskell是纯函数式语言的一个例子，因为没有办法操纵状态。机器代码是纯过程语言的一个例子，因为程序中的所有内容都是操作机器寄存器和内存状态的语句。

令人困惑的部分是，绝大多数编程语言同时包含表达式和语句，允许您混合使用范式。语言可以根据它们鼓励使用语句和表达式的程度被分类为更函数化或更过程化。

For example, C would be more functional than COBOL because a function call is an expression, whereas calling a sub program in COBOL is a statement (that manipulates the state of shared variables and doesn't return a value). Python would be more functional than C because it allows you to express conditional logic as an expression using short circuit evaluation (test && path1 || path2 as opposed to if statements). Scheme would be more functional than Python because everything in scheme is an expression.

你仍然可以在一种鼓励过程范式的语言中以函数式风格编写，反之亦然。只是在语言不鼓励的范式下写作更困难和/或更尴尬。