29bc664 · streamly · git.iko.soy

git.iko.soy/streamly

Add replicateM operation

commit29bc6648255eb15a084e5d704cc842c79c1d9198 authorHarendra Kumar <harendra.kumar@gmail.com> dateFri 16 Mar 2018, 02:41 (9 years ago) parent84542d2

3 files changed+19−1

compare with master

unifiedsplit

Changelog.md+1−1 src/Streamly/Prelude.hs+9 test/Main.hs+9

Changelog.md+1−1

@@ -1,7 +1,7 @@

11## Unreleased

33### Enhancements

4−* Add the `scan` operation for left scan of a stream

4+* Add `replicateM`, `scan` stream operations

55* Improve performance of some stream operations (`foldl`, `dropWhile`)

77### Bug Fixes

src/Streamly/Prelude.hs+9

@@ -59,6 +59,7 @@ module Streamly.Prelude

5959 , mapM

6060 , mapM_

6161 , sequence

62+ , replicateM

6263

6364 -- * Zipping

6465 , zipWith

@@ -431,6 +432,14 @@ sequence m = fromStream $ go (toStream m)

431432 yield a (Just x) = a >>= \b -> yld b (Just (go x))

432433 in (runStream m1) Nothing stop yield

433434

435+replicateM :: (Streaming t, Monad m) => Int -> m a -> t m a

436+replicateM n m = fromStream $ go n

437+ where

438+ go cnt = Stream $ \_ stp yld ->

439+ if cnt <= 0

440+ then stp

441+ else m >>= \a -> yld a (Just $ go (cnt - 1))

442+

434443------------------------------------------------------------------------------

435444-- Serially Zipping Streams

436445------------------------------------------------------------------------------

test/Main.hs+9

@@ -4,6 +4,7 @@

44module Main (main) where

66import Control.Concurrent (threadDelay)

7+import Control.Monad (replicateM)

78import Data.Foldable (forM_)

89import Data.List (sort)

910import Test.Hspec

@@ -637,6 +638,14 @@ mixedOps = do

637638streamOperations :: Streaming t => (t IO Int, [Int], Int) -> Spec

638639streamOperations (stream, list, len) = do

639640

641+ -- Generation

642+ it "replicateM" $ do

643+ let x = return (1 :: Int)

644+ str <- A.toList . serially $ A.replicateM len x

645+ lst <- replicateM len x

646+ return $ str == lst

647+ `shouldReturn` True

648+

640649 -- Filtering

641650 it "filter all out" $ transform (A.filter (> len)) (filter (> len))

642651 it "filter all in" $ transform (A.filter (<= len)) (filter (<= len))