[Haskell-cafe] Re: Shootout summary

[Donald Bruce Stewart]

neubauer:
> dons at cse.unsw.edu.au (Donald Bruce Stewart) writes:
> 
> >> > Fannkuch entry by Bertram Felgenhauer
> >> > Mandelbrot entry
> >> 
> >> I've done some benchmarking of the current entries for fannkuch and
> >> mandelbrot, and have proposed final entries for these two tests.
> 
> Using >>= of the list monad in the current Fannkuch proposal
> (permutations) hides some costly ++ applications that can be also
> optimized away:
> 
> Instead of writting
>  
>   permutations l = foldr perm' [l] [2..length l] 
>       where perm' n l = l >>= take n . iterate (rotate n)
>  
> saying something like 
> 
>   permutations l = foldr perm' [l] [2..length l]
>     
>   perm' n  = foldr (takeIter n (rotate n)) []
> 
>   takeIter :: Int -> (a -> a) -> a -> [a] -> [a]
>   takeIter 0 f x rest = rest 
>   takeIter n f x rest = x : takeIter (n-1) f (f x) rest
> 
> gains us another 5% or so.
  
Ah! Good idea Matthias.  I've updated the proposed entry on the wiki.

Cheers,
  Don