On Thu, Feb 26, 2009 at 2:13 PM, Edsko de Vries
On Thu, Feb 26, 2009 at 12:45:09PM -0300, Felipe Lessa wrote:
I'd advise you to see Control.Parallel.Strategies, specially the NFData class and the rnf function.
What is the time complexity of running rnf on a Data.Map? If it is O(n), then surely running rnf on my map after every 'map' operation is hardly going to speed things up?
I guess so. Maybe using mapAccum helps: import qualified Data.Map as M strictMap :: (a -> b) -> M.Map k a -> M.Map k b strictMap f m = case M.mapAccum f' () m of ((), m') -> m' where f' () x = x' `seq` ((), x') where x' = f x testStrictness mapper = m `seq` "Not strict." where m = mapper (const e) (M.singleton () ()) e = error "Strict!" :: () Testing: *Main> testStrictness M.map "Not strict." *Main> testStrictness strictMap "*** Exception: Strict! Don't know about efficiency, though :). HTH, -- Felipe.