74ce247 · streamly · git.iko.soy

git.iko.soy/streamly

Add Prelude#find, Prelude#lookup

commit74ce247d71f0a81f6926193c6913ef786342c09c authorVeladus <veladus@web.de> dateMon 23 Jul 2018, 21:04 (8 years ago) parenta39a35c

3 files changed+42−3

compare with master

unifiedsplit

src/Streamly/Prelude.hs+14−1 src/Streamly/Streams/StreamK.hs+25−1 test/Prop.hs+3−1

src/Streamly/Prelude.hs+14−1

@@ -105,6 +105,8 @@ module Streamly.Prelude

105105 , minimum

106106 , sum

107107 , product

108+ , lookup

109+ , find

108110

109111 -- *** Indices

110112 , findIndices

@@ -170,7 +172,7 @@ import Prelude

170172 hiding (filter, drop, dropWhile, take, takeWhile, zipWith, foldr,

171173 foldl, map, mapM, mapM_, sequence, all, any, sum, product, elem,

172174 notElem, maximum, minimum, head, last, tail, length, null,

173− reverse, iterate, init, and, or)

175+ reverse, iterate, init, and, or, lookup)

174176import qualified Prelude

175177import qualified System.IO as IO

176178

@@ -612,6 +614,17 @@ minimum m = S.minimum (toStreamS m)

612614maximum :: (Monad m, Ord a) => SerialT m a -> m (Maybe a)

613615maximum m = S.maximum (toStreamS m)

614616

617+-- | Looks the given key up, treating the given stream as an association list.

618+{-# INLINE lookup #-}

619+lookup :: (Monad m, Eq a) => a -> SerialT m (a, b) -> m (Maybe b)

620+lookup = K.lookup

621+

622+-- | Returns the first element of the stream satisfying the given predicate,

623+-- if any.

624+{-# INLINE find #-}

625+find :: Monad m => (a -> Bool) -> SerialT m a -> m (Maybe a)

626+find = K.find

627+

615628-- | Finds all the indices of elements satisfying the given predicate.

616629{-# INLINE findIndices #-}

617630findIndices :: IsStream t => (a -> Bool) -> t m a -> t m Int

src/Streamly/Streams/StreamK.hs+25−1

@@ -90,6 +90,8 @@ module Streamly.Streams.StreamK

9090 , minimum

9191 , maximum

9292 , findIndices

93+ , lookup

94+ , find

9395

9496 -- ** Map and Fold

9597 , mapM_

@@ -143,7 +145,7 @@ import Data.Semigroup (Semigroup(..))

143145import Prelude

144146 hiding (foldl, foldr, last, map, mapM, mapM_, repeat, sequence,

145147 take, filter, all, any, takeWhile, drop, dropWhile, minimum,

146− maximum, elem, notElem, null, head, tail, init, zipWith)

148+ maximum, elem, notElem, null, head, tail, init, zipWith, lookup)

147149import qualified Prelude

148150

149151import Streamly.SVar

@@ -675,6 +677,28 @@ maximum m = go Nothing (toStream m)

675677 else go (Just res) r

676678 in unStream m1 defState stop single yieldk

677679

680+{-# INLINE lookup #-}

681+lookup :: (IsStream t, Monad m, Eq a) => a -> t m (a, b) -> m (Maybe b)

682+lookup e m = go (toStream m)

683+ where

684+ go m1 =

685+ let single (a, b) | a == e = return $ Just b

686+ | otherwise = return Nothing

687+ yieldk (a, b) x | a == e = return $ Just b

688+ | otherwise = go x

689+ in unStream m1 defState (return Nothing) single yieldk

690+

691+{-# INLINE find #-}

692+find :: (IsStream t, Monad m) => (a -> Bool) -> t m a -> m (Maybe a)

693+find p m = go (toStream m)

694+ where

695+ go m1 =

696+ let single a | p a = return $ Just a

697+ | otherwise = return Nothing

698+ yieldk a x | p a = return $ Just a

699+ | otherwise = go x

700+ in unStream m1 defState (return Nothing) single yieldk

701+

678702{-# INLINE findIndices #-}

679703findIndices :: IsStream t => (a -> Bool) -> t m a -> t m Int

680704findIndices p = fromStream . go 0 . toStream

test/Prop.hs+3−1

@@ -10,7 +10,7 @@ import Control.Concurrent (MVar, takeMVar, putMVar, newEmptyMVar)

1010import Control.Monad (replicateM, replicateM_)

1111import Data.IORef (readIORef, modifyIORef, newIORef)

1212import Data.List (sort, foldl', scanl', findIndices, findIndex, elemIndices,

13− elemIndex)

13+ elemIndex, find)

1414import Data.Maybe (mapMaybe)

1515import GHC.Word (Word8)

1616

@@ -489,6 +489,8 @@ eliminationOps constr desc t = do

489489 prop (desc ++ " findIndex") $ eliminateOp constr (findIndex odd) $ (S.findIndex odd) . t

490490 prop (desc ++ " elemIndex") $ eliminateOp constr (elemIndex 3) $ (S.elemIndex 3) . t

491491

492+ prop (desc ++ " find") $ eliminateOp constr (find even) $ (S.find even) . t

493+

492494-- head/tail/last may depend on the order in case of parallel streams

493495-- so we test these only for serial streams.

494496serialEliminationOps