ByteString 的 chunksOf 模拟？

Question

我需要将字节串拆分为字节串列表，第一个潜水 100 个字符。对于列表，我可以使用 chunksOf 但不能使用 ByteString。

有什么正确的方法吗？

Answer 1

ByteString 和 Lazy.Bytestring 都有 splitAt functions which you can use to unfoldr 个列表。

import Data.List (unfoldr)
import Data.Int (Int64)

import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as Lazy

justWhen :: (a -> Bool) -> (a -> b) -> (a -> Maybe b)
justWhen f g a = if f a then Just (g a) else Nothing

nothingWhen :: (a -> Bool) -> (a -> b) -> (a -> Maybe b)
nothingWhen f = justWhen (not . f)

chunksOf :: Int -> BS.ByteString -> [BS.ByteString]
chunksOf x = unfoldr (nothingWhen BS.null (BS.splitAt x))

chunksOf' :: Int64 -> Lazy.ByteString -> [Lazy.ByteString]
chunksOf' x = unfoldr (nothingWhen Lazy.null (Lazy.splitAt x))

使用 OverloadedStrings

可以更轻松地为示例构建字节串

{-# LANGUAGE OverloadedStrings #-}

main = do
    print $ chunksOf 3 ""
    print $ chunksOf 3 "Hello World!"
    print $ chunksOf' 3 ""
    print $ chunksOf' 3 "Hello, World"

ByteString 的 chunksOf 模拟？

chunksOf analog for ByteString?

haskell

bytestring