ListZipper 模块 $ cabal install ListZipper Installed ListZipper-1.2.0.2 Prelude> :m +Data.List.Zipper Prelude Data.List.Zipper> Zipper 和 ListZipper Zipper 是一种带焦点(focus,也称游标, cursor)的数据结构.使用 Zipper 可以很方便的在底层数据结构中进行遍历,更新,插入,删除等操作. ListZipper 是建立在 List 这

这是<Two Dozen Short Lessons in Haskell>这本书的最后一章,第23章没有习题. 这一章里介绍了Haskell如果自定义一种类型,并且用一个双人博弈游戏为例子讲解了如何使用这些类型,里面简单介绍了Minimax算法. 至此,这本书全部学完,当然还没用Haskell写过什么大一点的程序,只是掌握了其基本概念. 1 A tree, in computer science, is an entity a with a root and two subtrees b w

Data.Text.Read Prelude> :set -XOverloadedStrings Prelude> :m +Data.Text.Read Prelude Data.Text.Read> decimal "123" Right (123,"") Prelude Data.Text.Read> decimal "abc" Left "input does not start with a digit&

Data.Typeable 利用 Data.Typeable,可以打印动态类型信息. class Typeable (a :: k) where typeRep# :: TypeRep a typeRep :: Typeable a => TypeRep a typeRep = typeRep# typeOf :: Typeable a => a -> TypeRep a typeOf _ = typeRep typeOf 函数可以返回某个值的类型信息. {-# LANGUAGE Der

安装 unordered-containers $ cabal install unordered-containers Installed unordered-containers-0.2.9.0 Prelude> import Data.HashSet as HashSet Prelude HashSet> :set -XOverloadedLists Prelude HashSet> Construction Prelude HashSet> empty fromList [

Data.Tree data Tree a = Node { rootLabel :: a, subForest :: Forest a } deriving (Eq, Read, Show) type Forest a = [Tree a] Data.Tree 是一种非空(存在根节点),可以有无限分支,每个节点均可有多路分支的Tree类型. Prelude Data.Tree> :t Node 1 Node 1 :: Num a => Forest a -> Tree a Prelud

Map Prelude> import Data.Map as Map Prelude Map> :set -XOverloadedLists Prelude Map> OverloadedLists GHC 提供了语言扩展 OverloadedLists. 不使用这个语言扩展,所有的列表字面量都属于 [] 类型. 如果使用这个语言扩展,那么所有的列表字面量就都属于 IsList l => l 类型. Map, Set, Vector, Text, Array 都是 IsList

安装 unordered-containers $ cabal install unordered-containers Installed unordered-containers-0.2.9.0 Prelude> import Data.HashMap.Lazy as HashMap Prelude HashMap> :set -XOverloadedLists Prelude HashMap> Construction Prelude HashMap> empty fromL

Data.Vector Construction Prelude V> import Data.Vector as V Prelude V> V.empty [] Prelude V> V.singleton 1 [1] Prelude V> V.replicate 5 1 [1,1,1,1,1] Prelude V> generate 5 (+1) [1,2,3,4,5] Prelude V> iterateN 5 (*2) 1 [1,2,4,8,16]

Data.Set Prelude> import Data.Set as Set Prelude Set> :set -XOverloadedLists Construction Prelude Set> empty fromList [] Prelude Set> singleton 5 fromList [5] Prelude Set> insert 3 [4,5] fromList [3,4,5] Prelude Set> delete 5 [3,4,5] fro

Data.Sequence Prelude> import Data.Sequence as Seq Prelude Seq> :set -XOverloadedLists Prelude Seq> Construction Prelude Seq> empty fromList [] Prelude Seq> singleton 3 fromList [3] Prelude Seq> 3 <| [4,5] fromList [3,4,5] Prelude Seq

Data.Tuple fst :: (a,b) -> a fst (x,_) = x snd :: (a,b) -> b snd (_,y) = y curry :: ((a, b) -> c) -> a -> b -> c curry f x y = f (x, y) uncurry :: (a -> b -> c) -> ((a, b) -> c) uncurry f p = f (fst p) (snd p) swap :: (a,b) -

Data.Maybe Prelude Data.Maybe> maybe "" show (Just 5) "5" Prelude Data.Maybe> maybe "" show Nothing "" Prelude Data.Maybe> isJust (Just 3) True Prelude Data.Maybe> isJust Nothing False Prelude Data.Maybe

"I worked up a full implementation as well but I decided that it was too complicated to post in the blog. What I was really trying to get across was that immutable data structures were possible and not that hard; a full-on finger tree implementation

haskell中的io模块主要是用于读写文件屏幕的,通过import IO来导入 其中有如下常用定义 data IOMode = ReadMode | WriteMode | AppendMode | ReadWriteMode openFile :: FilePath -> IOMode -> IO Handle hClose :: Handle -> IO () hIsEOF :: Handle -> IO Bool hGetChar :: Handle -> IO Ch

到haskell官方下载haskell的工具包: https://downloads.haskell.org/~platform/2014.2.0.0/Haskell%20Platform%202014.2.0.0%2064bit.signed.pkg adeMacBook-Pro:haskell_dev apple$ ghci GHCi, version : http://www.haskell.org/ghc/ :? for help Loading package ghc-prim ...

使用System.IO模块 使用函数 openBinaryFile :: FilePath -> IOMode -> IO Handle 打开文件 IOMode为 ReadWriteMode, 不然会截断文件 eg: h <- openFile "b.txt" ReadWriteModehPutChar h 'b'hPutChar h 'b'hPutChar h 'b'hPutChar h 'b'hPutChar h 'b'hClose h 如果处理二进制文件 要引入

"I know why you're here. ...why you hardly sleep, why night after night, you sit by your computer." Features of Haskell Purely functional Statical typed Lazy 1. Purely functional Every input has a corresponding output f(x) = x² + 1 Powerful func

<Brief History of Machine Learning> 介绍:这是一篇介绍机器学习历史的文章,介绍很全面,从感知机.神经网络.决策树.SVM.Adaboost到随机森林.Deep Learning. <Deep Learning in Neural Networks: An Overview> 介绍:这是瑞士人工智能实验室Jurgen Schmidhuber写的最新版本<神经网络与深度学习综述>本综述的特点是以时间排序,从1940年开始讲起,到60-80

Algebraic Data Types 入门 在前面的章节中,我们谈了一些 Haskell 内置的类型和 Typeclass.而在本章中,我们将学习构造类型和 Typeclass 的方法. 我们已经见识过许多类型,如 Bool.Int.Char.Maybe 等等,不过在 Haskell 中该如何构造自己的类型呢?好问题,一种方法是使用 data 关键字.首先我们来看看 Bool 在标准函式库中的定义: data Bool = False | True data 表示我们要定义一个新的类型.=