函数式编程所倡导使用的「不可变数据结构」如何保证性能？

如何评价 Meta 的代码搜索系统 Glean?

是否可以说 Contract 和 Type Inference 模糊了静态类型和动态类型的界限？

函数式编程是否适用于超大型项目？

现代语言的closure是如何处理的？

rust是不是一个no gc 的 haskell？

类型应该是一等公民吗?

Haskell 和 Scheme, 哪一个更适合用于生产环境?

haskell中的callcc有什么用？

如何写一个简单的编译器？

Call By Need语义下如何做Partial Evaluation？

为什么HASKELL这类语言要用代数概念描述类型的组合（ADT） 而不是看作集合去运算和组合？

Haskell等语言中的模式匹配在C++中如何实现？

编程语言需要哪些机制才能支持模式匹配(pattern match)？

未来什么编程语言和开发技术会比较吃香呢？

Lambda 表达式、Block、闭包与匿名函数之间有什么区别？和 λ 演算有什么关系？

怎样理解 Partial Evaluation？

如何理解 Free Monad？

为什么函数式语言里有recursive data type但没有recursive function type？

类型推导是否可以理解为一种编译期计算？

应该如何理解Profunctor？

Call by name 的语言能模拟 call by value 吗？

dependent type之上还有更高级的类型系统吗？

Haskell 的 Typeclass 怎么理解？

Higher-kinded type到底有什么用？

Edward Kmett 的这个讲座在讲什么？

该如何理解Monad？

如何理解 Extensible Effects?

如何理清 lens 这个库的各个组件，熟悉各种高级玩法？

Haskell 的带界量化多态和 Java/C# 的接口动态委派，哪一个更有利于优化？灵活性更好？

如何理解Haskell中的Arrow及其用途?

怎么看待王垠对 Haskell 的评价？

精通 Haskell 是一种怎样的体验？

如何解释 Haskell 中的单子（Monad）？

怎么理解“一个单子（Monad）说白了不过就是自函子范畴上的一个幺半群而已”?

怎样用简单的语言解释 monad？

如何理解Monad Transformer？有哪些资料可以帮助理解它？

state monad 为什么wrap的是一个 Function ？

为什么applicative不定义为monoid的子类？

GHC扩展-XRankNTypes是什么？如何理解forall .？

List的Applicative instance应该怎么写？

Haskell 这段代码该如何理解？

Haskell 里面的 Functor 是个什么概念？

函数式编程和反应式编程（reactive programming）有什么区别？

Haskell引入Applicative functor有什么意义？

函数式编程如何优雅的处理很多 多个函数都要用到的 参数？

Even with OverloadedRecordDot, Haskell’s records are still bad, they’re just not awful.

软件行业中，错误的做法往往得到更多的资源。下面是两个例子： 一个公司里面，技术债务最多的团队，员工最多。 问题最多的软件库或编程语言，产生最多的话题。

The IO monad wraps computations in the following context: "This computation can read information from or write information to the terminal, file system, operating system, and/or network". If you want to get user input, print a message to the user, read information from a file, or make a network call, you'll need to do so within the IO Monad. These are "side effects". We cannot perform them from "pure" Haskell code.

Haskell is the best functional programming language in the world and Neural Networks are functionsThis is the main motivation behind Hasktorch which lets you discover new kinds of Neural Network architectures by combining functional operators

Commonly the above definition is called the identity function. But in fact we should think of it as a whole family of functions. We should really say that id is an identity function for all types a. In other words, for every type T you might come up with, there is an identity function called id, which is of type T -> T. This is the type-checker’s view anyway, and by turning on the RankNTypes extension we can be explicit about that in our code: {-# LANGUAGE RankNTypes #-} id :: forall a. a -> a id x = x

Now it is much clearer that id is really a family of infinitely many functions. It is fair to say that it is an abstract function (as opposed to a concrete one), because its type abstracts over the type variable a. The common and proper mathematical wording is that the type is universally quantified (or often just quantified) over a.

It also adds safety through a property called parametricity. If we pretend that there are no infinite loops or exceptions (it’s okay to do that, so we will do it throughout this article), then the function is actually fully determined by its type. In other words, if we see the type a -> a, we know that the corresponding value must be the identity function.

In other words you cannot choose the definition of a value based on its type (for now).

function (or in the case of type classes, we call these methods)

If you can tell that two types are equal or not equal, that type belongs in the Eq type class.

Programming languages These will probably expose my ignorance pretty nicely.

Nix is a purely functional package manager. This means that it treats packages like values in purely functional programming languages such as Haskell — they are built by functions that don’t have side-effects, and they never change after they have been built.

This package takes a more declarative approach, and talks about events rather than signals. Widgets emit event values, and these values can be mapped and transformed into other values as the event propagates up the tree of widgets.

Haskell

-- FizzBuzz
module Main where

import Control.Monad

main :: IO ()
main = forM_ [1..100] $ \n -> putStrLn . concat . take 2 $
    ["Fizz" | n `mod` 3 == 0] ++ 
    ["Buzz" | n `mod` 5 == 0] ++ 
    ["", show n]

Deeper Stack Knowledge

(== 10)

Whereas normal type classes represent predicates on types (each type is either an instance of a type class or it isn’t), multi-parameter type classes represent relations on types

A History of Haskell:Being Lazy With Class

FRP library

foldMap :: Monoid m -> (a -> m) -> t a -> m

The notion behind it was that one could decompose, e.g., Applicative into an instance of the Pointed typeclass and an instance of the Apply typeclass (giving apply :: f (a -> b) -> f a -> f b) and an instance of Pointed, such that the two interact properly.