83cbe5d · streamly · git.iko.soy

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Add distribute_

83cbe5dHarendra Kumar7 years ago

src/Streamly/Internal/Data/Fold.hs+17

@@ -146,6 +146,7 @@ module Streamly.Internal.Data.Fold

146

147 , tee

148 , distribute

149+ , distribute_

149

150

150 -- * Partitioning

151 -- * Partitioning

151

152

@@ -866,6 +867,22 @@ distribute :: Monad m => [Fold m a b] -> Fold m a [b]

866distribute [] = foldNil

867distribute [] = foldNil

867distribute (x:xs) = foldCons x (distribute xs)

868distribute (x:xs) = foldCons x (distribute xs)

868

869

870+-- | Like 'distribute' but for folds that return (), this can be more efficient

871+-- than 'distribute' as it does not need to maintain state.

872+--

873+{-# INLINE distribute_ #-}

874+distribute_ :: Monad m => [Fold m a ()] -> Fold m a ()

875+distribute_ fs = Fold step initial extract

876+ where

877+ initial = Prelude.mapM (\(Fold s i e) ->

878+ i >>= \r -> return (Fold s (return r) e)) fs

879+ step ss a = do

880+ Prelude.mapM_ (\(Fold s i _) -> i >>= \r -> s r a >> return ()) ss

881+ return ss

882+ extract ss = do

883+ Prelude.mapM_ (\(Fold _ i e) -> i >>= \r -> e r) ss

884+ return ()

885+

869------------------------------------------------------------------------------

886------------------------------------------------------------------------------

870-- Partitioning

887-- Partitioning

871------------------------------------------------------------------------------

888------------------------------------------------------------------------------