writer + binary

gistfile1.hs

{-# LANGUAGE PackageImports #-}
import Data.Binary.Get
import "mtl" Control.Monad.Writer
import qualified Data.ByteString.Lazy as SL
import Data.Word

main = do
  l <- SL.readFile "test"
  let (a,b) = runWriter $ next l 0
  print a 
  print b
  where 
    next bs off | SL.null bs = return off 
                | otherwise = do
                    let (t,bs',off') = runGetState readChunk bs off
                    tell [t]
                    next bs' off'
    readChunk :: Get Word16
    readChunk = getWord16le