How to make Haskell Network.Browser do gzip compression?

Question

The Haskell Network.Browser module does not seem to do any compression. How can I configure it to perform gzip compression, assuming the server supports it (or does not return to compression if it is not)?

Answer 1

Here's a short version of the “fairly simple” rkhayrov solution related to:

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

I did some tests with the following:

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

It works on both Yahoo (compressed) and Google (uncompressed).