Re: [Haskell-cafe] Shootout favoring imperative code

Sebastian Sylvan wrote:

On 1/5/06, Chris Kuklewicz wrote:

...

There is no need to beat a dead horse, though. This benchmark sets out to test fgets / atoi, and that is all. There are better benchmarks to spend time on.

I agree. The benchmark really is about how fast you can call low-level IO system calls. But since Haskell is a high-level language it's natural that it's a bit difficult to get access to these unsafe (but fast) low-level functions.

There's probably a bit more to it. First off, one could legitimately argue that (liftM lines getContents) is the Haskell way to do line oriented IO. The real question is, why does the fast solution have to be ugly

foreign import ccall "stdio.h" fgets :: CString -> Int -> Ptr CFile ->IO CString foreign import ccall safe "stdlib.h" atoi :: CString -> Int foreign import ccall safe "stdio.h &(*stdin)" c_stdin :: Ptr CFile

and why does the idiomatic solution have to be slow? | main = print . sum . map read . lines =<< getContents The biggest hit is probably the construction of a huge String as linked list, which cannot be deforested away (not with the foldr/build mechanism anyway). Assuming we find a better representation for Strings, we could make some headway here and in many other benchmarks. So I think, just by replacing String and along with it getContents, lines and read, we will get competitive speed and retain the ability to handle arbitrarily long lines. Of course, the shootout wouldn't care for a feature that is otherwise quite important in practice... Anyway, I'll try try to come up with something and then follow up on this. Udo. -- A man always needs to remember one thing about a beautiful woman: Somewhere, somebody's tired of her.