+1 LGTM On 14.07.2016 05:16, David Feuer wrote:
As I describe in https://github.com/haskell/deepseq/issues/17 it is possible to implement an NFData instance for any Foldable type, and we can offer a function to help do that:
data Unit = Unit
instance Monoid Unit where mempty = Unit Unit `mappend` Unit = Unit -- strict in both arguments, unlike ()
rnfFoldable :: (Foldable f, NFData a) => f a -> () rnfFoldable xs = foldMap (\x -> rnf x `seq` Unit) xs `seq` ()
This could be used like so:
instance NFData a => NFData (F a) where rnf = rnfFoldable
This version forces from left to right. It would be possible to offer another version that forces from right to left:
data Unit2 = Unit2
instance Monoid Unit2 where mempty = Unit2 x `mappend` Unit2 = x `seq` Unit2
rnfFoldableRTL :: (Foldable f, NFData a) => f a -> () rnfFoldableRTL xs = foldMap (\x -> rnf x `seq` Unit2) xs `seq` () _______________________________________________ Libraries mailing list Libraries@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/libraries
-- Andreas Abel <>< Du bist der geliebte Mensch. Department of Computer Science and Engineering Chalmers and Gothenburg University, Sweden andreas.abel@gu.se http://www2.tcs.ifi.lmu.de/~abel/