[Haskell-cafe] Difference between Lazy ByteStrings and Strings in alex

Duncan Coutts duncan.coutts at worc.ox.ac.uk
Wed Feb 14 04:33:41 EST 2007

On Tue, 2007-02-13 at 22:43 -0500, Jefferson Heard wrote:
> It was suggested that I might derive some performance benefit from using lazy 
> bytestrings in my tokenizer instead of regular strings.  Here's the code that 
> I've tried.  Note that I've hacked the "basic" wrapper code in the Lazy 
> version, so the code should be all but the same.  The only thing I had to do 
> out of the ordinary was write my own 'take' function instead of using the 
> substring function provided by Data.Lazy.ByteString.Char8.  The take function 
> I used was derived from the one GHC uses in GHC.List and produces about the 
> same code.

If you use the latest darcs version of alex and the "basic-bytestring"
wrapper then you don't have to write any of your own take functions.

Actually, lazy ByteString are still not as optimised as I would like.
There are still too many indirections. That's something I'm working on
at the moment.


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