266148c · streamly · git.iko.soy

git.iko.soy/streamly

Add yield and repeat APIs

commit266148c84aac40f28ca30b8de0427cf291c99a67 authorHarendra Kumar <harendra.kumar@gmail.com> dateSat 23 Jun 2018, 07:35 (8 years ago) parent9c85811

4 files changed+39−31

compare with master

unifiedsplit

Changelog.md+5 src/Streamly/Prelude.hs+5−3 src/Streamly/Streams/StreamK.hs+11−14 src/Streamly/Tutorial.hs+18−14

Changelog.md+5

@@ -4,6 +4,11 @@

55* `once` has been deprecated and renamed to `yieldM`

7+### Enhancements

9+* Add `yield` to construct a singleton stream from a pure value

10+* Add `repeat` to generate an infinite stream by repeating a pure value

11+

712## 0.3.0

813

914### Breaking changes

src/Streamly/Prelude.hs+5−3

@@ -41,10 +41,12 @@ module Streamly.Prelude

4141 -- * Construction

4242 -- | Primitives to construct or inspect a stream.

4343 nil

44− , consM

45− , (|:)

44+ , K.yield

45+ , K.yieldM

4646 , cons

4747 , (.:)

48+ , consM

49+ , (|:)

4850

4951 -- * Generation by Unfolding

5052 , unfoldr

@@ -53,8 +55,8 @@ module Streamly.Prelude

5355 -- * Special Generation

5456 -- | Generate a monadic stream from an input structure, a seed or a

5557 -- generation function.

56− , K.yieldM

5758 , replicateM

59+ , K.repeat

5860 , repeatM

5961 , iterate

6062 , iterateM

src/Streamly/Streams/StreamK.hs+11−14

@@ -199,9 +199,14 @@ mkStream k = fromStream $ Stream $ \svr stp sng yld ->

199199nil :: IsStream t => t m a

200200nil = fromStream $ Stream $ \_ stp _ _ -> stp

201201

202−-- faster than yieldM because there is no bind.

203−-- | Create a singleton stream from a pure value. Same as @yieldM (return a)@

204−-- but more efficient.

202+-- Faster than yieldM because there is no bind. Usually we can construct a

203+-- stream from a pure value using "pure" in an applicative, however in case of

204+-- Zip streams pure creates an infinite stream.

205+-- | Create a singleton stream from a pure value. In monadic streams, 'pure' or

206+-- 'return' can be used in place of 'yield', however, in Zip applicative

207+-- streams 'pure' is equivalent to 'repeat'.

208+--

209+-- @since 0.4.0

205210yield :: IsStream t => a -> t m a

206211yield a = fromStream $ Stream $ \_ _ single _ -> single a

207212

@@ -257,17 +262,6 @@ infixr 5 .:

257262(.:) :: IsStream t => a -> t m a -> t m a

258263(.:) = cons

259264

260−-- | Constructs a stream by adding a monadic action at the head of an existing

261−-- stream. For example:

262−--

263−-- @

264−-- > toList $ getLine \`consM` getLine \`consM` nil

265−-- hello

266−-- world

267−-- ["hello","world"]

268−-- @

269−--

270−-- @since 0.2.0

271265{-# INLINE consMSerial #-}

272266consMSerial :: (Monad m) => m a -> Stream m a -> Stream m a

273267consMSerial m r = Stream $ \_ _ _ yld -> m >>= \a -> yld a r

@@ -336,6 +330,9 @@ runStream m = go (toStream m)

336330-- Special generation

337331-------------------------------------------------------------------------------

338332

333+-- | Generate an infinite stream by repeating a pure value.

334+--

335+-- @since 0.4.0

339336repeat :: IsStream t => a -> t m a

340337repeat a = let x = cons a x in x

341338

src/Streamly/Tutorial.hs+18−14

@@ -185,7 +185,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

185185-- represents a single IO action whereas the 'Serial' monad represents a series

186186-- of IO actions. The only change you need to make to go from 'IO' to 'Serial'

187187-- is to use 'runStream' to run the monad and to prefix the IO actions with

188−-- either 'once' or 'liftIO'. If you use liftIO you can switch from 'Serial'

188+-- either 'yieldM' or 'liftIO'. If you use liftIO you can switch from 'Serial'

189189-- to IO monad by simply removing the 'runStream' function; no other changes

190190-- are needed unless you have used some stream specific composition or

191191-- combinators.

@@ -347,13 +347,17 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

347347-- ["hello","world"]

348348-- @

349349--

350−-- To create a singleton stream from a pure value use 'pure' and to create a

351−-- singleton stream from a monadic action use 'once'.

350+-- To create a singleton stream from a pure value use 'yield' or 'pure' and to

351+-- create a singleton stream from a monadic action use 'yieldM'. Note that in

352+-- case of Zip applicative streams "pure" repeats the value to generate an

353+-- infinite stream.

352354--

353355-- @

354356-- > S.'toList' $ 'pure' 1

355357-- [1]

356−-- > S.'toList' $ S.'once' 'getLine'

358+-- > S.'toList' $ 'yield' 1

359+-- [1]

360+-- > S.'toList' $ S.'yieldM' 'getLine'

357361-- hello

358362-- ["hello"]

359363-- @

@@ -506,7 +510,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

506510-- seconds. After the delay it prints the number of seconds it slept.

507511--

508512-- @

509−-- delay n = S.'once' $ do

513+-- delay n = S.'yieldM' $ do

510514-- threadDelay (n * 1000000)

511515-- tid \<- myThreadId

512516-- putStrLn (show tid ++ ": Delay " ++ show n)

@@ -737,7 +741,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

737741--

738742-- @

739743-- main = 'runStream' . 'asyncly' $ traced (sqrt 9) '<>' traced (sqrt 16) '<>' traced (sqrt 25)

740−-- where traced m = S.'once' (myThreadId >>= print) >> return m

744+-- where traced m = S.'yieldM' (myThreadId >>= print) >> return m

741745-- @

742746-- @

743747-- ThreadId 40

@@ -859,7 +863,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

859863-- google = get "https://www.google.com/search?q=haskell"

860864-- bing = get "https://www.bing.com/search?q=haskell"

861865-- duckduckgo = get "https://www.duckduckgo.com/?q=haskell"

862−-- get s = S.'once' (httpNoBody (parseRequest_ s) >> putStrLn (show s))

866+-- get s = S.'yieldM' (httpNoBody (parseRequest_ s) >> putStrLn (show s))

863867-- @

864868--

865869-- The polymorphic version of the binary operation '<>' of the 'Parallel' type

@@ -918,7 +922,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

918922-- 'runStream' $ 'foldWith' 'async' (map delay [1..10])

919923-- 'runStream' $ 'foldMapWith' 'async' delay [1..10]

920924-- 'runStream' $ 'forEachWith' 'async' [1..10] delay

921−-- where delay n = S.'once' $ threadDelay (n * 1000000) >> print n

925+-- where delay n = S.'yieldM' $ threadDelay (n * 1000000) >> print n

922926-- @

923927

924928-- $nesting

@@ -988,7 +992,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

988992-- import "Streamly"

989993-- import qualified "Streamly.Prelude" as S

990994--

991−-- main = 'runStream' $ forever $ S.once getLine >>= S.once . putStrLn

995+-- main = 'runStream' $ forever $ S.yieldM getLine >>= S.yieldM . putStrLn

992996-- @

993997--

994998-- When multiple streams are composed using this style they nest in a DFS

@@ -1003,7 +1007,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

10031007-- main = 'runStream' $ do

10041008-- x <- S.'fromFoldable' [1,2]

10051009-- y <- S.'fromFoldable' [3,4]

1006−-- S.'once' $ putStrLn $ show (x, y)

1010+-- S.'yieldM' $ putStrLn $ show (x, y)

10071011-- @

10081012-- @

10091013-- (1,3)

@@ -1100,7 +1104,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

11001104-- main = 'runStream' . 'asyncly' $ do

11011105-- x <- S.'fromFoldable' [1,2]

11021106-- y <- S.'fromFoldable' [3,4]

1103−-- S.'once' $ putStrLn $ show (x, y)

1107+-- S.'yieldM' $ putStrLn $ show (x, y)

11041108-- @

11051109-- @

11061110-- (1,3)

@@ -1125,7 +1129,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

11251129-- main = 'runStream' . 'wSerially' $ do

11261130-- x <- S.'fromFoldable' [1,2]

11271131-- y <- S.'fromFoldable' [3,4]

1128−-- S.once $ putStrLn $ show (x, y)

1132+-- S.yieldM $ putStrLn $ show (x, y)

11291133-- @

11301134-- @

11311135-- (1,3)

@@ -1153,7 +1157,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

11531157-- main = 'runStream' . 'wAsyncly' $ do

11541158-- x <- S.'fromFoldable' [1,2]

11551159-- y <- S.'fromFoldable' [3,4]

1156−-- S.'once' $ putStrLn $ show (x, y)

1160+-- S.'yieldM' $ putStrLn $ show (x, y)

11571161-- @

11581162-- @

11591163-- (1,3)

@@ -1202,7 +1206,7 @@ import Control.Monad.Trans.Class (MonadTrans (lift))

12021206-- sz <- sizes

12031207-- cl <- colors

12041208-- sh <- shapes

1205−-- S.'once' $ putStrLn $ show (sz, cl, sh)

1209+-- S.'yieldM' $ putStrLn $ show (sz, cl, sh)

12061210--

12071211-- where

12081212--