Streamly.External.ByteString.Lazy

Documentation

readChunks :: Monad m => Unfold m ByteString (Array Word8)

Unfold a lazy ByteString to a stream of Array Words.

read :: Monad m => Unfold m ByteString Word8

Unfold a lazy ByteString to a stream of Word8

toChunks :: Monad m => ByteString -> SerialT m (Array Word8)

Convert a lazy ByteString to a serial stream of Array Word8.

fromChunks :: Monad m => SerialT m (Array Word8) -> m ByteString

Convert a serial stream of Array Word8 to a lazy ByteString.

IMPORTANT NOTE: This function is lazy only for lazy monads (e.g. Identity). For strict monads (e.g. IO) it consumes the entire input before generating the output. For IO monad please use fromChunksIO instead.

For strict monads like IO you could create a newtype wrapper to make the monad bind operation lazy and lift the stream to that type using hoist, then you can use this function to generate the bytestring lazily. For example you can wrap the IO type to make the bind lazy like this:

newtype LazyIO a = LazyIO { runLazy :: IO a } deriving (Functor, Applicative)

liftToLazy :: IO a -> LazyIO a
liftToLazy = LazyIO

instance Monad LazyIO where
  return = pure
  LazyIO a >>= f = LazyIO (unsafeInterleaveIO a >>= unsafeInterleaveIO . runLazy . f)

fromChunks can then be used as, {--} fromChunksIO :: SerialT IO (Array Word8) -> IO ByteString fromChunksIO str = runLazy (fromChunks (S.hoist liftToLazy str))

fromChunksIO :: SerialT IO (Array Word8) -> IO ByteString

Convert a serial stream of Array Word8 to a lazy ByteString in the IO monad.