On Thursday 10 June 2010 13:28:36, Luca Ciciriello wrote:
Hi All.
I've two question about Data Parallel Haskell.
I'm trying some experiment using DPH and I've wrote a little program using the functions lengthP and mapP. I've imported the module GHC.PArr and I've informed the compiler that I want to use some language extension using the line {-# LANGUAGE PArr #-}. All works fine. Looking around I've saw that some code examples use {-# LANGUAGE PArr, ParallelListComp #-} instead.
Parallel list-comprehensions are something different from parallel arrays. I think it's not implied by PArr, so if you use both features, you need to specify both.
The my first question is: Which is the difference in using or not the extension ParallelListComp? Seems that my program works fine with or without this extension (if I omit the extension PArr I've some compilation errors).
Then you probably only use parallel arrays and not parallel list- comprehensions (which are just syntactic sugar for the families of zip[With]N functions).
The second question is: Have I to use the option -threaded when compile my program?
Would make sense. It wouldn't be able to profit from multiple cores without. Compile with -threaded and run with +RTS -Nk (for a reasonable value of k on your box).
I'm using Haskell Platform (GHC 6.12.1) on MacOS X 10.6.3
Thanks in advance for any answer.
Luca.