On Wed, Aug 05, 2009 at 06:48:02AM -0600, Denis Bueno wrote:
[...] This is because of the [] instance. I, myself, have been bitten by this, but I don't think it's a flaw in the library -- there are plenty of people using the library who haven't complained about the instance.
If the instance isn't right for you, write a new one. That's what I did.
The problem is that people shouldn't be reinventing the wheel everytime. I propose adding something along the lines of this snippet to binary (untested): import Control.Applicative import Control.Monad (replicateM_) -- | Provides a new instance of 'Binary' to lists that 'put's and -- 'get's using chunks instead of forcing the whole spine of -- the list before writing the first byte. This enconding is -- less space-efficient in the disk, though, having an overhead -- of @1 + (length xs `div` 255)@ bytes instead of only four -- bytes (independently of list size), the overhead of the -- default instance. newtype Chunked a = Chunked {unChunked :: [a]} instance Binary (Chunked a) where -- This 'put' should be good enough. put = mapM_ putChunk . chunks 255 . unChunked where chunks 255 [] = [(0,[])] -- not []! chunks _ [] = [] chunks _ xs = let (i,f) = splitAt 255 xs len = length i in (len,i) : chunks len f putChunk (len,xs) = putWord8 len >> mapM_ put xs -- I don't know if this get works nicely, though. get = getWord8 >>= go [] where go acc 0 = return $ concat $ reverse acc go acc len = do xs <- replicateM_ len get len' <- if len == 255 then getWord8 else return 0 go (xs:acc) len' -- Felipe.