Re: [Haskell-cafe] newbie questions (read, etc., with Data.ByteString.Lazy.Char8)

6 Oct 2008


      the problem is that using readInt is actually _as slow_, at least using my
test script :-((

On Tue, Oct 7, 2008 at 5:12 AM, Don Stewart  wrote:
...
666wman:
...
a slight modification to compile it :
change:
   where sumFile = sum . map read . L.words
   to :
   where sumFile = sum . map (read . L.unpack) . L.words
but it's actually _slower_ than the non-bytestring version.
Never unpack a bytestring.
import qualified Data.ByteString.Lazy.Char8 as S
main = print . go 0 =<< S.getContents
     where
       go n s = case S.readInt s of
                       Nothing     -> n
                       Just (k,t)  -> go (n+k) (S.tail t)
Assuming you're reading int, integers or doubles.