Ironically, there's a TODO comment about that in the source of
Data.ByteString.Lazy, just below 'copy':
http://hackage.haskell.org/packages/archive/bytestring/0.9.0.4/doc/html/src/...
-- TODO defrag func that concatenates block together that are below a threshold
-- defrag :: ByteString -> ByteString
2010/1/23 Gregory Crosswhite
I would say that counts as cheating because it assumes that knowledge of the input in advance. However, I wonder how it would perform if there were a "reChunk" function that lazily built a new lazy ByteString by merging smaller chunks together --- i.e., it would keep pullings chunks from the ByteString until it reached some threshold size, merge them into a single strict ByteString chunk, and then recursively continue processing the rest of the lazy ByteString in this manner.
Cheers, Greg
On Jan 22, 2010, at 7:30 AM, Tom Nielsen wrote:
It seems to me this indicates that the big expense here is the call into the I/O system.
So let's make fewer I/O calls:
import Control.Monad import qualified Data.ByteString.Char8 as S import System.IO
null_str1 = S.concat $ take 1000 $ repeat $ S.pack "null"
n1 = 5000000 `div` 1000
main = withBinaryFile "out3.json" WriteMode $ \h -> do hPutStr h "[" replicateM_ n1 (S.hPutStr h null_str1) hPutStr h "]" --- this is 10x faster. Whether this is cheating or not depends on what John actually wants to do.
Tom
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