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1. parConcatMap :: forall (m :: Type -> Type) a b . MonadAsync m => (Config -> Config) -> (a -> Stream m b) -> Stream m a -> Stream m b

   streamly	Streamly.Internal.Data.Stream.Prelude

   Map each element of the input to a stream and then concurrently evaluate and concatenate the resulting streams. Multiple streams may be evaluated concurrently but earlier streams are perferred. Output from the streams are used as they arrive. Definition:

   >>> parConcatMap modifier f stream = Stream.parConcat modifier $ fmap f stream
   

   Examples:

   >>> f cfg xs = Stream.fold Fold.toList $ Stream.parConcatMap cfg id $ Stream.fromList xs
   

   The following streams finish in 4 seconds:

   >>> stream1 = Stream.fromEffect (delay 4)
   
   >>> stream2 = Stream.fromEffect (delay 2)
   
   >>> stream3 = Stream.fromEffect (delay 1)
   
   >>> f id [stream1, stream2, stream3]
   1 sec
   2 sec
   4 sec
   [1,2,4]
   

   Limiting threads to 2 schedules the third stream only after one of the first two has finished, releasing a thread:

   >>> f (Stream.maxThreads 2) [stream1, stream2, stream3]
   ...
   [2,1,4]
   

   When used with a Single thread it behaves like serial concatMap:

   >>> f (Stream.maxThreads 1) [stream1, stream2, stream3]
   ...
   [4,2,1]
   

   >>> stream1 = Stream.fromList [1,2,3]
   
   >>> stream2 = Stream.fromList [4,5,6]
   
   >>> f (Stream.maxThreads 1) [stream1, stream2]
   [1,2,3,4,5,6]
   

   Schedule all streams in a round robin fashion over the available threads:

   >>> f cfg xs = Stream.fold Fold.toList $ Stream.parConcatMap (Stream.interleaved True . cfg) id $ Stream.fromList xs
   

   >>> stream1 = Stream.fromList [1,2,3]
   
   >>> stream2 = Stream.fromList [4,5,6]
   
   >>> f (Stream.maxThreads 1) [stream1, stream2]
   [1,4,2,5,3,6]
   

2. mconcat :: Monoid a => [a] -> a

   constrained-categories	Control.Category.Constrained.Prelude

   Fold a list using the monoid. For most types, the default definition for mconcat will be used, but the function is included in the class definition so that an optimized version can be provided for specific types.

   >>> mconcat ["Hello", " ", "Haskell", "!"]
   "Hello Haskell!"
   

3. mconcat :: Monoid a => [a] -> a

   copilot-language	Copilot.Language.Prelude

   Fold a list using the monoid. For most types, the default definition for mconcat will be used, but the function is included in the class definition so that an optimized version can be provided for specific types.

   >>> mconcat ["Hello", " ", "Haskell", "!"]
   "Hello Haskell!"
   

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