On Tue, 17 Jan 2012, Johan Tibell wrote:
Try it out on the Criterion benchmarks in the source repo. I'd be curious to see the results.
Okay, I never intended to try and replace the existing operations with a lens based one, but now you've got me curious to try. Here is my fastLens implementation: fastLens :: Key -> IntMap a -> (IntMap a -> (a -> IntMap a) -> a -> c) -> (IntMap a -> (a -> IntMap a) -> c) -> c fastLens k = k `seq` go where go t@(Bin p m l r) c1 c2 | nomatch k p m = c2 t (\x -> join k (Tip k x) p t) | zero k m = go l (updateContL c1) (updateContL c2) | otherwise = go r (updateContR c1) (updateContR c2) where updateContL c dl il = c (bin p m dl r) (\x -> bin p m (il x) r) updateContR c dr ir = c (bin p m l dr) (\x -> bin p m r (ir x)) go t@(Tip ky y) c1 c2 | k == ky = c1 Nil (Tip ky) y | otherwise = c2 t (\x -> join k (Tip k x) ky t) go Nil _ c2 = c2 Nil (Tip k) lookup :: Key -> IntMap a -> Maybe a lookup k t = fastLens k t (\_ _ -> Just) (\_ _ -> Nothing) insert :: Key -> a -> IntMap a -> IntMap a insert k x t = fastLens k t (\_ it _ -> it x) (\_ it -> it x) delete :: Key -> IntMap a -> IntMap a delete k t = fastLens k t (\dt _ _ -> dt) (\dt _ -> dt) update :: (a -> Maybe a) -> Key -> IntMap a -> IntMap a update f k t = fastLens k t (\dt it x -> maybe dt it (f x)) (\dt _ -> dt) alter :: (Maybe a -> Maybe a) -> Key -> IntMap a -> IntMap a alter f k t = fastLens k t (\dt it x -> maybe dt it (f (Just x))) (\dt it -> maybe dt it (f Nothing)) lens :: Key -> IntMap a -> (Maybe a -> IntMap a, Maybe a) lens k t = fastLens k t (\dt it x -> (maybe dt it,Just x)) (\dt it -> (maybe dt it,Nothing)) (See also: https://github.com/roconnor/containers/tree/FastLens) How do I use criterion to benchmark this? -- Russell O'Connor http://r6.ca/ ``All talk about `theft,''' the general counsel of the American Graphophone Company wrote, ``is the merest claptrap, for there exists no property in ideas musical, literary or artistic, except as defined by statute.''