Okey, I tried pipes back 3.0 but did not understand much and moved on. Now
I got (a bit) more experience and thought I could try this out again. I'm
writing a IRC bot. So, I got some question regarding this; I have a
Producer that yields ByteString for each line my bot receives to a Pipe
which yields Message which is the internal format I deal with IRC messages.
I've got a bit confused about how to do this though, and it feels like
there's a more streaming way of doing this. So here's my code so far:
import Pipes
import Pipes.Network.TCP.Safe
import Data.Monoid ((<>))
import qualified Data.ByteString.Char8 as B
import Control.Monad (forever)
import Tob.IRC.Types (Message(..))
import Tob.IRC.Decode (decodeIrc)
server :: (MonadSafe m, Base m ~ IO) => HostName -> ServiceName ->
Producer' ByteString m ()
server s p = fromConnect 4096 s p >~ go
go chunk = do
let (line, rest) = B.breakSubstring "\r\n" chunk
notDone = do
more <- await
if B.null more
then error "received null"
else parser $ chunk <> more
bs <- await
if B.null rest
then notDone
else yield $ line <> take 2 rest
getDone = do
more <- await
if B.null more
then return ()
else go $ chunk
parser :: Pipe ByteString Message IO r
parser = forever $ do
bs <- await
case decodeIrc bs of
Just m -> yield m
_ -> putStrLn $ "failed to parse: " ++ show bs
(wrote on my phone, so haven't tried if it compiles but it will get an
general idea of how my design is intended)
So I basically wait till I got a full bytestring till I yield it to next
pipe, then I parse using my parser that rely on the attoparsec parser that
is wrapped in maybeResult.
So what I wonder:
* Is this really a streaming way of doing it?
* Is there perhaps a way to use the attoparsec parser as a Pipe in a better
fashion? (what happens when something Fail or Partial results?)
Thanks, Karl-Oskar "klrr" Rikås
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