问题描述
我希望压缩我的应用程序的网络流量。根据(最新的?),似乎是一个非常受欢迎的解决方案。 zlib的接口使用使用的数据类型。 code>:
sendTo :: Socket - >字符串 - > SockAddr - > IO Int
recvFrom :: Socket - > Int - > IO(String,Int,SockAddr)
所以要压缩我的字符串,我需要一些方法来转换字符串转换为 ByteString ,反之亦然。
借助的帮助,我发现:
Data.ByteString.Char8 pack :: String - > ByteString
尝试使用它:
Prelude Codec.Compression.Zlib Data.ByteString.Char8>压缩(packboo)
< interactive>:1:10:
无法匹配预期的类型'Data.ByteString.Lazy.Internal.ByteString'
针对推断类型`ByteString'
在`compress'的第一个参数中,即`(packboo)'
在表达式中:compress(packboo)
在`it':it = compress(packboo)
失败,因为(?)不同类型的 ByteString ?
所以基本上:
- 有几种类型的 ByteString ?什么类型,为什么?
- 将字符串 s转换为 ByteString c $ c> s?
顺便说一句,我发现它可以和 Data.ByteString.Lazy一起工作。 Char8 的 ByteString ,但我仍然很感兴趣。
I wish to compress my application's network traffic.
According to the (latest?) "Haskell Popularity Rankings", zlib seems to be a pretty popular solution. zlib's interface uses ByteStrings:
compress :: ByteString -> ByteString decompress :: ByteString -> ByteString
I am using regular Strings, which are also the data types used by read, show, and Network.Socket:
sendTo :: Socket -> String -> SockAddr -> IO Int recvFrom :: Socket -> Int -> IO (String, Int, SockAddr)
So to compress my strings, I need some way to convert a String to a ByteString and vice-versa.With hoogle's help, I found:
Data.ByteString.Char8 pack :: String -> ByteString
Trying to use it:
Prelude Codec.Compression.Zlib Data.ByteString.Char8> compress (pack "boo") <interactive>:1:10: Couldn't match expected type `Data.ByteString.Lazy.Internal.ByteString' against inferred type `ByteString' In the first argument of `compress', namely `(pack "boo")' In the expression: compress (pack "boo") In the definition of `it': it = compress (pack "boo")
Fails, because (?) there are different types of ByteString ?
So basically:
- Are there several types of ByteString? What types, and why?
- What's "the" way to convert Strings to ByteStrings?
Btw, I found that it does work with Data.ByteString.Lazy.Char8's ByteString, but I'm still intrigued.
There are two kinds of bytestrings: strict (defined in Data.Bytestring.Internal) and lazy (defined in Data.Bytestring.Lazy.Internal). zlib uses lazy bytestrings, as you've discovered.
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