3387346 · streamly · git.iko.soy

git.iko.soy/streamly

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Add trace to folds

3387346Adithya Kumar4 years ago

core/src/Streamly/Internal/Data/Fold.hs+14

compare with master

unifiedsplit

@@ -132,6 +132,7 @@ module Streamly.Internal.Data.Fold

132 , scanMany

133 , postscan

134 , indexed

135+ , trace

135

136

136 -- ** Zipping Input

137 -- ** Zipping Input

137 , zipWithM

138 , zipWithM

@@ -291,6 +292,7 @@ where

291#include "inline.hs"

292#include "inline.hs"

292#include "ArrayMacros.h"

293#include "ArrayMacros.h"

293

294

295+import Control.Monad (void)

294import Control.Monad.IO.Class (MonadIO(..))

296import Control.Monad.IO.Class (MonadIO(..))

295import Data.Bifunctor (first)

297import Data.Bifunctor (first)

296import Data.Bits (shiftL, shiftR, (.|.), (.&.))

298import Data.Bits (shiftL, shiftR, (.|.), (.&.))

@@ -401,6 +403,18 @@ mapMaybe f = lmap f . filter isJust . lmap fromJust

401-- Transformations on fold inputs

403-- Transformations on fold inputs

402------------------------------------------------------------------------------

404------------------------------------------------------------------------------

403

405

406+-- | Apply a monadic function to each element flowing through and discard the

407+-- results.

408+--

409+-- >>> Stream.fold (Fold.trace print Fold.drain) $ (Stream.enumerateFromTo (1 :: Int) 2)

410+-- 1

411+-- 2

412+--

413+-- /Pre-release/

414+{-# INLINE trace #-}

415+trace :: Monad m => (a -> m b) -> Fold m a r -> Fold m a r

416+trace f = lmapM (\x -> void (f x) >> return x)

417+

404-- rename to lpipe?

418-- rename to lpipe?

405--

419--

406-- | Apply a transformation on a 'Fold' using a 'Pipe'.

420-- | Apply a transformation on a 'Fold' using a 'Pipe'.