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-- A simple test program which takes a url on the commandline
-- and outputs the contents to stdout.
-- ghc --make -package HTTP get.hs -o get
import Data.Char (intToDigit)
import Network.HTTP
import Network.URI
import System.Environment (getArgs)
import System.Exit (exitFailure)
import System.IO (hPutStrLn, stderr)
main =
do
args <- getArgs
case args of
[addr] -> case parseURI addr of
Nothing -> err "Could not parse URI"
Just uri -> do
cont <- get uri
putStr cont
_ -> err "Usage: get <url>"
err :: String -> IO a
err msg = do
hPutStrLn stderr msg
exitFailure
get :: URI -> IO String
get uri =
do
eresp <- simpleHTTP (request uri)
resp <- handleE (err . show) eresp
case rspCode resp of
(2,0,0) -> return (rspBody resp)
_ -> err (httpError resp)
where
showRspCode (a,b,c) = map intToDigit [a,b,c]
httpError resp = showRspCode (rspCode resp) ++ " " ++ rspReason resp
request :: URI -> Request
request uri = Request{ rqURI = uri,
rqMethod = GET,
rqHeaders = [],
rqBody = "" }
handleE :: Monad m => (ConnError -> m a) -> Either ConnError a -> m a
handleE h (Left e) = h e
handleE _ (Right v) = return v
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