Simon Marlow wrote:
Bulat Ziganshin wrote:
Hello Chris,
Monday, January 23, 2006, 12:27:53 PM, you wrote:
CK> The only mutable data structure that come with GHC besides arrays is CK> Data.Hashtable, which is not comptetitive with OCaml Hashtbl or DMD's CK> associative arrays (unless there is something great hidden under CK> Data.Graph). Is there any hope for GHC 6.6? Does anyone have pointers to CK> an existing library at all? Perl and Python and Lua also have excellent CK> built in hashtable capabilities. Where is a good library for Haskell?
1) are you used "+RTS -A10m" / "+RTS -H100m"?
2) Simon Marlow optimized something in the IOArray handling, but i don't understand that is changed. see http://cvs.haskell.org/trac/ghc/ticket/650
Much of the GC overhead of Data.Hash should be gone in GHC 6.6. I also have an improved implementation of Data.Hash from Jan-Willem Maessen to import, but that will be 6.6 rather than 6.4.2.
Cheers, Simon
That is good to hear. The benchmark's tests take 1,250,000 pre-generated strings as the keys. At the end, the string keys are 18 characters long, drawn randomly from a set of 4 characters. So the hash computations are a nontrivial hit. Using -A400m I get 39s down from 55s. That is the best Data.HashTable time I have seen. (Using -A10m and -A100m were a little slower). Using my over optimized c-code hashtable I get 12.3 seconds. The associative arrays in OCaml and D are still faster. So you see why I long for GHC 6.6. Is Jan-Willem Maessen's Hash available anywhere? I could benchmark it.