[Haskell-cafe] Data.Binary.encode slower than show

Grzegorz Chrupała pitekus at gmail.com
Sun Jul 26 16:27:41 EDT 2009

Hi all,
I have a piece of code where I'm serializing a datastructure with the
following type [(Int, (Map DType (IntMap Int)))], using Binary.encode
The thing is it is very slow: actually quite a bit slower than just using
This seems rather suspicious. Any idea what could be going on?

import qualified Data.Map as Map
import qualified Data.IntMap as IntMap
import Data.IntMap ((!))
import Vector
import Atom
import Control.Monad.State
import Indexing (indexBy)
import Data.List (foldl')
import System
import System.IO
import Debug.Trace
import qualified Data.Binary as Binary
import qualified Data.ByteString.Lazy as BS

data DType = Fol | For | Sol | Sor deriving (Eq,Enum,Ord,Show,Read)
instance Binary.Binary DType where
   get = do x <- Binary.get
            return (toEnum x)
   put x = Binary.put (fromEnum x)

type Word = Int
type Count = Int
type WordMap = IntMap.IntMap

find = IntMap.findWithDefault IntMap.empty

distReps ::    Map.Map (Word,Word) Count
           -> [(Int, (Map.Map DType (WordMap Count)))]
distReps bidict =
   let bigrams = Map.toList bidict
       for = indexBy id bigrams
       fol = indexBy swap bigrams
       ws  = map (fst . fst) bigrams
       r = flip map ws
           $ \w -> (w,Map.fromList [ (Fol , find w fol)
                                           , (For , find w for)
                                           , (Sol , sox for fol w )
                                           , (Sor , sox fol for w ) ])
   in trace (show $ r == r)  r
sox :: WordMap (WordMap Count)
   -> WordMap (WordMap Count)
   -> Word
   -> WordMap Count
sox fox foy w =
   let xs = IntMap.keys (find w fox)
       f !z x = let xv = find x foy
                in xv == xv `seq` z `plus` xv
   in foldl' f IntMap.empty xs

swap (!a,!b) = (b,a)

readBigrams = fmap (map (\ [w,w',c] -> ((w,w'),read c))
               . map words
                     . lines )
main = do
 [f] <- getArgs
 bigrams <- readBigrams
 let (bigrams',as) = flip runState empty (atomize bigrams)
     dr = distReps (Map.fromList bigrams')
 write f dr
 hPutStrLn stderr "Done this"
 write (f++".atom") as

--write f d =  writeFile f (show d)
write f d = BS.writeFile f (Binary.encode d)

atomize xs = mapM f xs
   where f ((w,w'),!i) = do
           !i_w <- toAtom w'
           !i_w' <- toAtom w
           let r = ((i_w,i_w'),i)
           r == r `seq` return r


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