Hello Gregory, Friday, August 25, 2006, 3:08:09 AM, you wrote:
Some performance data: using unsafeIOToST to write log messages directly to the output, the simulation does 10^7 state updates in about 45 seconds on my 1.5 GHz ppc G4. Using LogT, with a list of strings as the monoid, it takes about 7 minutes to do the same, and the system swaps heavily during the last few minutes. Not surprising, given that the mappend operation is not very efficient for the list monoid.
are you sure that you know how monads are implemented? IO/ST monads just organize order of execution, without any penalty comparing to imperative languages. but other monads and all monad transformers add their data to the tuple passed between monad operations. and this makes their execution significantly slower. you can read more about this in http://sigfpe.blogspot.com/2006/08/you-could-have-invented-monads-and.html about multi-threading - you can (and should!) use ghc's internal concurrency with forkIO. it is a perfect way - with minimal overhead and ability to use any Haskell features in each thread without fighting against multi-threading implementation -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com