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streamly/src/Streamly/Internal/Data/Stream/Zip/Concurrent.hs
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1{-# LANGUAGE UndecidableInstances #-}
2-- |
3-- Module : Streamly.Internal.Data.Stream.Concurrent
4-- Copyright : (c) 2017 Composewell Technologies
5-- License : BSD-3-Clause
6-- Maintainer : streamly@composewell.com
7-- Stability : experimental
8-- Portability : GHC
9--
10-- To run examples in this module:
11--
12-- >>> import qualified Streamly.Prelude as Stream
13--
14module Streamly.Internal.Data.Stream.Zip.Concurrent
15 (
16 ZipConcurrent (..)
17 )
18where
20import Streamly.Internal.Data.Stream (Stream)
21import Streamly.Internal.Data.Stream.Concurrent (MonadAsync, zipWith)
23import qualified Streamly.Internal.Data.Stream as Stream (repeat)
24import Prelude hiding (map, repeat, zipWith)
26-- $setup
27-- >>> import qualified Streamly.Internal.Data.Stream as Stream
28-- >>> import qualified Streamly.Data.Fold as Fold
29--
31newtype ZipConcurrent m a = ZipConcurrent {getZipConcurrent :: Stream m a}
32 deriving (Functor)
34-- | An IO stream whose applicative instance zips streams concurrently.
35--
36-- >>> s = ZipConcurrent $ Stream.fromList [1, 2, 3]
37-- >>> x = (,,) <$> s <*> s <*> s
38-- >>> Stream.fold Fold.toList (getZipConcurrent x)
39-- [(1,1,1),(2,2,2),(3,3,3)]
40--
41-- @since 0.9.0
43instance MonadAsync m => Applicative (ZipConcurrent m) where
44 pure = ZipConcurrent . Stream.repeat
46 {-# INLINE (<*>) #-}
47 ZipConcurrent m1 <*> ZipConcurrent m2 = ZipConcurrent $ zipWith id m1 m2