如何讓Haskell的Network.Browser做gzip壓縮？

Question

Haskell的Network.Browser模塊似乎沒有做任何壓縮。我怎樣才能配置它，以便它假定服務器支持它進行gzip壓縮（或者如果不支持則不會回退到壓縮）？

Answer 1

這裏的「相當容易」解決方案rkhayrov指的快速版本：

import Codec.Compression.GZip (decompress) 
import Control.Arrow (second) 
import Control.Monad (liftM) 
import qualified Data.ByteString.Lazy as B 
import Network.Browser 
import Network.HTTP (Request, Response, getRequest, getResponseBody, rspBody) 
import Network.HTTP.Headers (HasHeaders, HeaderName (..), findHeader, replaceHeader) 
import Network.TCP (HStream, HandleStream) 
import Network.URI (URI, parseURI) 

gzipRequest :: URI -> BrowserAction (HandleStream B.ByteString) (URI, Response B.ByteString) 
gzipRequest 
    = liftM (second unzipIfNeeded) 
    . request 
    . replaceHeader HdrAcceptEncoding "gzip" 
    . defaultGETRequest_ 
    where 
    unzipIfNeeded rsp 
     | isGz rsp = rsp { rspBody = decompress $ rspBody rsp } 
     | otherwise = rsp 
     where 
     isGz rsp = maybe False (== "gzip") $ findHeader HdrContentEncoding rsp 

我跑瞭如下幾個測試：

main = print =<< rspBody . snd <$> (getResponse =<< head <$> getArgs) 
    where 
    getResponse = browse . gzipRequest . fromJust . parseURI 

它適用於預期兩個Yahoo（壓縮）和Google（未壓縮）主頁。