我在这里看到很多关于函数式语言的讨论。为什么你要使用传统语言而不是传统语言呢?他们在哪些方面做得更好?他们更不擅长什么?理想的函数式编程应用程序是什么?


当前回答

我要指出的是,你所说的关于函数式语言的一切,大约20年前,大多数人都在谈论面向对象语言。在那时候,OO是很常见的:

* The average corporate programmer, e.g. most of the people I work with, will not understand it and most work environments will not let you program in it
* It's not really taught at universities (or is it nowadays?)
* Most applications are simple enough to be solved in normal IMPERATIVE ways

改变必须来自某个地方。无论接受过早期技术培训的人是否认为变革没有必要,有意义的重要变革都会发生。尽管当时有很多人反对,但你认为向OO的转变是好的吗?

其他回答

因为FP在生产力、可靠性和可维护性方面有显著的好处。多核可能是一个杀手级应用程序,最终让大公司在大量遗留代码的情况下转换。此外,即使是像c#这样的大型商业语言,也因为多核问题而呈现出一种独特的函数风格——副作用根本不适合并发性和并行性。

我不认为“普通”程序员不能理解它。他们会的,就像他们最终理解了面向对象编程一样(它同样神秘和怪异,如果不是更神秘的话)。

此外,大多数大学都教授FP,许多甚至将其作为第一门编程课程。

我一直对“下一件大事”持怀疑态度。很多时候,下一个大事件纯粹是历史的偶然,无论技术好坏,它都在正确的时间出现在正确的地点。例如:c++, Tcl/Tk, Perl。所有的技术都是有缺陷的,都非常成功,因为它们被认为要么解决了当时的问题,要么与根深蒂固的标准几乎相同,或者两者兼而有之。函数式编程可能确实很棒,但这并不意味着它会被采用。

But I can tell you why people are excited about functional programming: many, many programmers have had a kind of "conversion experience" in which they discover that using a functional language makes them twice as productive (or maybe ten times as productive) while producing code that is more resilient to change and has fewer bugs. These people think of functional programming as a secret weapon; a good example of this mindset is Paul Graham's Beating the Averages. Oh, and his application? E-commerce web apps.

自2006年初以来,也有一些关于函数式编程和并行的讨论。因为像Simon Peyton Jones这样的人至少从1984年开始就一直在担心并行性,所以在函数式语言解决多核问题之前,我不会屏住呼吸。但它确实解释了目前一些额外的话题。

In general, American universities are doing a poor job teaching functional programming. There's a strong core of support for teaching intro programming using Scheme, and Haskell also enjoys some support there, but there's very little in the way of teaching advanced technique for functional programmer. I've taught such a course at Harvard and will do so again this spring at Tufts. Benjamin Pierce has taught such a course at Penn. I don't know if Paul Hudak has done anything at Yale. The European universities are doing a much better job; for example, functional programming is emphasized in important places in Denmark, the Netherlands, Sweden, and the UK. I have less of a sense of what's happening in Australasia.

我一定是糊涂了,但我还是不明白。是否有像f#这样的函数式语言编写的小型应用程序的实际例子,你可以查看源代码,并了解如何以及为什么使用这种方法比c#更好?

函数式编程已经存在很长一段时间了,因为LISP是最早拥有编译器的语言之一,而且自从MIT的LISP机器问世以来。这不是一种新的范式(OO更新得多),但主流软件平台倾向于用易于转换为汇编语言的语言编写,它们的api非常倾向于命令式代码(UNIX使用C, Windows使用C, Macintosh使用Pascal和后来的C)。

我认为过去几年的新创新是api的多样性,尤其是在平台api无关紧要的web开发领域。因为你没有直接对Win32 API或POSIX API进行编码,这就给了人们尝试函数式语言的自由。

你最近有关注编程语言的发展吗?所有主流编程语言的每一个新版本似乎都从函数式编程中借用了越来越多的特性。

Closures, anonymous functions, passing and returning functions as values used to be exotic features known only to Lisp and ML hackers. But gradually, C#, Delphi, Python, Perl, Javascript, have added support for closures. Its not possible for any up-and-coming language to be taken seriously without closures. Several languages, notably Python, C#, and Ruby have native support for list comprehensions and list generators. ML pioneered generic programming in 1973, but support for generics ("parametric polymorphism") has only become an industry standard in the last 5 years or so. If I remember correctly, Fortran supported generics in 2003, followed by Java 2004, C# in 2005, Delphi in 2008. (I know C++ has supported templates since 1979, but 90% of discussions on C++'s STL start with "here there be demons".)

是什么让这些功能吸引程序员?这应该是显而易见的:它帮助程序员编写更短的代码。如果想要保持竞争力,未来所有的语言都将至少支持闭包。在这方面,函数式编程已经成为主流。

大多数应用程序都很简单 可以用正常的面向对象方法解决

谁说不能用函数式编程来处理简单的事情?并不是每个函数程序都需要是编译器、定理证明器或大型并行通信交换机。除了更复杂的项目外,我还经常使用f#来编写临时脚本。