git.iko.soy/streamly
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Implement nub in Fold.Window module
40a4bbcRanjeet Kumar Ranjan
core/src/Streamly/Internal/Data/Fold/Window.hs+41−2
compare with master
unifiedsplit
@@ -35,6 +35,7 @@ module Streamly.Internal.Data.Fold.Window
35 --
35 --
36 lmap
36 lmap
37 , cumulative
37 , cumulative
38+ , nub
38
39
39 -- ** Sums
40 -- ** Sums
40 , length
41 , length
@@ -59,11 +60,13 @@ import Streamly.Internal.Data.Fold.Type (Fold(..), Step(..))
59import Streamly.Internal.Data.Tuple.Strict
60import Streamly.Internal.Data.Tuple.Strict
60 (Tuple'(..), Tuple3Fused' (Tuple3Fused'))
61 (Tuple'(..), Tuple3Fused' (Tuple3Fused'))
61
62
62−import Prelude hiding (length, sum, minimum, maximum)
63+import qualified Data.Map as Map
63−
64import qualified Streamly.Internal.Data.Fold.Type as Fold
64import qualified Streamly.Internal.Data.Fold.Type as Fold
65import qualified Streamly.Internal.Data.Ring.Foreign as Ring
65import qualified Streamly.Internal.Data.Ring.Foreign as Ring
66
66
67+import Prelude hiding (length, sum, minimum, maximum)
68+
69+
67-- $setup
70-- $setup
68-- >>> import Data.Bifunctor(bimap)
71-- >>> import Data.Bifunctor(bimap)
69-- >>> import qualified Streamly.Data.Fold as Fold
72-- >>> import qualified Streamly.Data.Fold as Fold
@@ -309,3 +312,39 @@ maximum n = fmap (fmap snd) $ range n
309{-# INLINE mean #-}
312{-# INLINE mean #-}
310mean :: forall m a. (Monad m, Fractional a) => Fold m (a, Maybe a) a
313mean :: forall m a. (Monad m, Fractional a) => Fold m (a, Maybe a) a
311mean = Fold.teeWith (/) sum length
314mean = Fold.teeWith (/) sum length
315+
316+-- | Drop repeated elements within the specified
317+-- tumbling window in the stream.
318+-- /Pre-release/
319+--
320+-- >>> import qualified Streamly.Prelude as S
321+-- >>> S.fold nub $ S.fromList [(1, Nothing), (1, Nothing), (3, Nothing), (4, Just 1)]
322+-- fromList [(1,1),(3,1),(4,1)]
323+--
324+{-# INLINE nub #-}
325+nub :: (Monad m, Ord a) => Fold m (a, Maybe a) (Map.Map a Int)
326+nub = Fold step initial extract
327+
328+ where
329+
330+ initial =
331+ return $ Partial Map.empty
332+
333+ updateRefCounts new map0 = return $ Map.insertWith (+) new (1::Int) map0
334+
335+ alter a m1 (Just v) =
336+ if v == 1
337+ then do
338+ _ <- return $ Map.delete a m1
339+ return Nothing
340+ else return $ Just (v -1)
341+ alter _ _ Nothing = error "Invalid old element"
342+
343+ step map0 (new, mOld) = do
344+ m1 <- updateRefCounts new map0
345+ Partial <$>
346+ case mOld of
347+ Just a -> Map.alterF (alter a m1) a m1
348+ Nothing -> return m1
349+
350+ extract = return
src/Streamly/Internal/Data/Stream/IsStream/Transform.hs−12
@@ -78,7 +78,6 @@ module Streamly.Internal.Data.Stream.IsStream.Transform
78 , uniq
78 , uniq
79 , uniqBy
79 , uniqBy
80 , nubBy
80 , nubBy
81− , nubWindowBy
82 , prune
81 , prune
83 , repeated
82 , repeated
84
83
@@ -942,17 +941,6 @@ nubBy :: -- (IsStream t, Monad m) =>
942 (a -> a -> Bool) -> t m a -> t m a
941 (a -> a -> Bool) -> t m a -> t m a
943nubBy = undefined -- fromStreamD . D.nubBy . toStreamD
942nubBy = undefined -- fromStreamD . D.nubBy . toStreamD
944
943
945−-- | Drop repeated elements within the specified tumbling window in the stream.
946−--
947−-- @nubBy = nubWindowBy maxBound@
948−--
949−-- /Unimplemented/
950−--
951−{-# INLINE nubWindowBy #-}
952−nubWindowBy :: -- (IsStream t, Monad m) =>
953− Int -> (a -> a -> Bool) -> t m a -> t m a
954−nubWindowBy = undefined -- fromStreamD . D.nubWithinBy . toStreamD
955−
956-- | Deletes the first occurrence of the element in the stream that satisfies
944-- | Deletes the first occurrence of the element in the stream that satisfies
957-- the given equality predicate.
945-- the given equality predicate.
958--
946--