Haskell语言学习笔记（21）Array

Ix

数组下标类型

Prelude> :m +Data.ArrayPrelude Data.Array> data Colour = Red | Orange | Yellow | Green | Blue | Indigo | Violet deriving (Show,Eq,Ord,Ix)Prelude Data.Array> range (Yellow,Blue)[Yellow,Green,Blue]Prelude Data.Array> index (Yellow,Blue) Green1Prelude Data.Array> inRange (Yellow,Blue) RedFalse

Array UArray

数组类型，类型参数有两个，下标类型 i 和元素类型 e。
Array是装箱数组类型（元素为指针）
UArray是非装箱数组类型（元素为实体）

Prelude> :m +Data.ArrayPrelude Data.Array> a = array (1,10) ((1,1) : [(i, i + a!(i-1)) | i <- [2..10]]) Prelude Data.Array> :t aa :: (Ix e, Num e, Enum e) => Array e ePrelude Data.Array> a!1055Prelude Data.Array> bounds a(1,10)Prelude Data.Array> indices a[1,2,3,4,5,6,7,8,9,10]Prelude Data.Array> elems a[1,3,6,10,15,21,28,36,45,55]Prelude Data.Array> assocs a[(1,1),(2,3),(3,6),(4,10),(5,15),(6,21),(7,28),(8,36),(9,45),(10,55)]Prelude Data.Array> array ((1,1),(2,2)) [((2,1),"C"),((1,2),"B"),((1,1),"A"),((2,2),"D")] ! (2,2)"D"Prelude Data.Array> array ('a','c') [('a',"AAA"),('b',"BBB"),('c',"CCC")] ! 'b'"BBB"

Prelude> :m +Data.Array.UnboxedPrelude Data.Array.Unboxed> a = listArray (1,10) [1..10] :: UArray Int IntPrelude Data.Array.Unboxed> aarray (1,10) [(1,1),(2,2),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9),(10,10)]Prelude Data.Array.Unboxed> a // [(1,100),(2,99)]array (1,10) [(1,100),(2,99),(3,3),(4,4),(5,5),(6,6),(7,7),(8,8),(9,9),(10,10)]

IOArray IOUArray

在IO monad中使用的数组。

函数 参数 功能 newArray 区间和初值 新建带初值的数组 readArray 数组和下标 读取数组某个元素的值 writeArray 数组,下标和值 设置数组某个元素的值 getElems 数组 读取数组所有元素的值

Prelude> :m +Data.Array.IOPrelude Data.Array.IO> a <- newArray (0, 2) 0 :: IO (IOUArray Int Int)Prelude Data.Array.IO> getElems a[0,0,0]Prelude Data.Array.IO> writeArray a 0 3Prelude Data.Array.IO> readArray a 03Prelude Data.Array.IO> writeArray a 1 6Prelude Data.Array.IO> getElems a[3,6,0]Prelude Data.Array.IO> writeArray a 2 7Prelude Data.Array.IO> getElems a[3,6,7]

STArray STUArray

在ST monad中使用的数组。

-- https://stackoverflow.com/questions/8197032/starray-documentation-for-newbies-and-state-st-related-questionsimport Control.Monadimport Control.Monad.STimport Data.Array.STimport Data.Array.UnboxedprimesUpto :: Int -> [Int]primesUpto n = [p | (p, True) <- assocs $ sieve n]sieve :: Int -> UArray Int Boolsieve n = runSTUArray $ do    sieve <- newArray (2, n) True    forM_ [2..n] $ \p -> do        isPrime <- readArray sieve p        when isPrime $ do            forM_ [p*2, p*3 .. n] $ \k -> do                writeArray sieve k False    return sievemain = print $ primesUpto 100