[Haskell-cafe] [RFC] benchmarks of bytestrings, teaser

[Daniel Fischer]

Am Sonntag, 16. Dezember 2007 04:07 schrieb Don Stewart:

> ------------------------------------------------------------------------
> Program 7:
>
>      ==============================
>      hs/space-xxxxx-foldl.hs:
>      {-# LANGUAGE BangPatterns #-}
>
>      cnt   :: String -> Int
>      cnt bs        = foldl (\sum c -> if c == ' ' then sum+1 else sum) 0 bs
>
>      main = do s <- getContents
>              print (cnt s)
>
> Hmm. Lazy accumulator eh, on String?  Should exhibit a space leak.

Doesn't (with -O2, at least), seems ghc's strictness analyser did a good job.
It is indeed about 10* slower than ByteStrings, but very memory friendly - 
and, actually on my machine it's faster (not much) than Data.List.foldl' .
And, again on my machine, Programme 3 is almost as slow when compiled with 
6.8.1 and twice as slow when compiled with 6.6.1.

> Nice little benchmark.
>
> -- Don

Cheers,
Daniel