[Haskell-cafe] memory needed for SAX parsing XML

19 Apr 2010

      Hello haskellers!

I'm trying to process an xml file with as little footprint as possible. 
SAX is alright for my case, and I think that's the lightest way 
possible. So, I'm looking at HaXml.SAX

I'm surprised to see that it takes about 56-60 MB of ram. This seems 
constant relative to xml file size, which is expected. Only slightly 
depends on it as I recursively traverse the list of sax events. But it 
seems like too much.

The size of the file is from 1MB to 20MB.

The code is something like this

main = do
     (fn:_) <- getArgs
     h <- openFile fn ReadMode
     c <- hGetContents h
     let out = proc $ fst $ saxParse fn c
     putStrLn out
     getChar

-- 'f' is tail-recursive
-- 'i' is used only to ensure that the list is completely traversed

proc es = show $ f es 0
  where f :: [SaxElement] -> Int -> Int
        f (SaxElementOpen name _ : rest) i = f rest i
        f (_ : rest) i = f rest i
        f [] i = i

Thanks for you thoughts!

-- 
Daniil Elovkov