哈斯克爾[字符]以字節串

Question

main :: IO() 
main = do 
    let a = ("teeeeeeeeeeeeest","teeeeeeeeeeeest") 
    b <- app a 
    print b 

的應用希望（字節字符串，字節字符串）不是（[字符]，[字符]） 我怎麼能轉換嗎？

Answer 1

您可以轉換String s到ByteString s的Data.ByteString.Char8.pack（或其懶惰ByteString版）如果您的String只包含ASCII值，或者你感興趣的只是每個Char的後八位，

import qualified Data.ByteString.Char8 as C 
main :: IO() 
main = do 
    let a = ("teeeeeeeeeeeeest","teeeeeeeeeeeest") 
    b <- app $ (\(x,y) -> (C.pack x, C.pack y)) a 
    print b 

如果您的String包含非ASCII Char，並且您只對最後8位感興趣，則需要其他編碼，如Data.ByteString.UTF8.fromString。

Answer 2

你可以嘗試：

import qualified Data.ByteString.Char8 as B --to prevent name clash with Prelude 
B.pack "Hello, world" 

很多有用的功能，可以在這裏找到：

http://www.haskell.org/ghc/docs/latest/html/libraries/bytestring/Data-ByteString-Char8.html

你也可以使用Data.ByteString.Lazy.Char8 懶惰的字節串

http://hackage.haskell.org/packages/archive/bytestring/latest/doc/html/Data-ByteString-Lazy-Char8.html#v:pack