On 1/6/06, Udo Stenzel <[EMAIL PROTECTED]> wrote: > Sebastian Sylvan wrote: > > On 1/5/06, Chris Kuklewicz <[EMAIL PROTECTED]> 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.
It would be neat if the PackedString library contained functions such as hGetLine etc. It does have a function for reading from a buffer, but it won't stop at a newline... But yeah, fast string manipulation is difficult when using a linked-list representation... /S -- Sebastian Sylvan +46(0)736-818655 UIN: 44640862 _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
