On Thursday 26 March 2009 15:39:12 Manlio Perillo wrote:
I also tried with Data.HashTable: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2902
but memory usage is 703 MB, and execution time is about 4.5 times slower!
This is due to a perf bug in GHC's GC implementation that causes it to traverse entire arrays when a single element has been changed. Hence the Haskell is over an order of magnitude slower than most languages and even slower than Python (!). The purely functional trees that you also used are apparently the idiomatic Haskell workaround but, of course, they are extremely inefficient and still over an order of magnitude slower than any decent hash table. For comparison: Haskell hash table: 44s Haskell map: 7s F# hash table: 0.7s -- Dr Jon Harrop, Flying Frog Consultancy Ltd. http://www.ffconsultancy.com/?e