Pipes.Concurrent.PQueue

A variant of Pipes.Concurrent that uses a Finger Tree-based Priority Queue (TPQueue) instead of a normal TQueue.

Documentation

spawn :: Ord p => IO (Output (p, a), Input a, STM ())

Spawn a mailbox to store prioritized messages in a Mailbox. Using recv on the Input will return Just the minimal element, or Nothing if the mailbox is closed.

This function is analogous to Pipes.Concurrent.spawn' Unbounded, but it uses a TPQueue instead of a TQueue to store messages.

withSpawn :: Ord p => ((Output (p, a), Input a) -> IO r) -> IO r

withSpawn passes its enclosed action an Output and Input like you'd get from spawn, but automatically seals them after the action completes. This can be used when you need the sealing behavior available from spawn, but want to work at a bit higher level:

withSpawn buffer $ \(output, input) -> ...

withSpawn is exception-safe, since it uses bracket internally.

Re-exports from Pipes.Concurrent

newtype Input a :: * -> *

An exhaustible source of values

recv returns Nothing if the source is exhausted

Constructors

Input

Fields

• recv :: STM (Maybe a)

Instances

Monad Input

Methods

(>>=) :: Input a -> (a -> Input b) -> Input b

(>>) :: Input a -> Input b -> Input b

return :: a -> Input a

fail :: String -> Input a

Functor Input

Methods

fmap :: (a -> b) -> Input a -> Input b

(<$) :: a -> Input b -> Input a

Applicative Input

Methods

pure :: a -> Input a

(<*>) :: Input (a -> b) -> Input a -> Input b

liftA2 :: (a -> b -> c) -> Input a -> Input b -> Input c

(*>) :: Input a -> Input b -> Input b

(<*) :: Input a -> Input b -> Input a

Alternative Input

Methods

empty :: Input a

(<|>) :: Input a -> Input a -> Input a

some :: Input a -> Input [a]

many :: Input a -> Input [a]

MonadPlus Input

Methods

mzero :: Input a

mplus :: Input a -> Input a -> Input a

Monoid (Input a)

Methods

mempty :: Input a

mappend :: Input a -> Input a -> Input a

mconcat :: [Input a] -> Input a

newtype Output a :: * -> *

An exhaustible sink of values

send returns False if the sink is exhausted

Constructors

Output

Fields

• send :: a -> STM Bool

Instances

Contravariant Output

This instance is useful for creating new tagged address, similar to elm's Signal.forwardTo. In fact elm's forwardTo is just 'flip contramap'

Methods

contramap :: (a -> b) -> Output b -> Output a

(>$) :: b -> Output b -> Output a

Divisible Output

Methods

divide :: (a -> (b, c)) -> Output b -> Output c -> Output a

conquer :: Output a

Decidable Output

Methods

lose :: (a -> Void) -> Output a

choose :: (a -> Either b c) -> Output b -> Output c -> Output a

Monoid (Output a)

Methods

mempty :: Output a

mappend :: Output a -> Output a -> Output a

mconcat :: [Output a] -> Output a

fromInput :: MonadIO m => Input a -> Producer' a m ()

Convert an Input to a Producer

fromInput terminates when the Input is exhausted.

toOutput :: MonadIO m => Output a -> Consumer' a m ()

Convert an Output to a Consumer

toOutput terminates when the Output is exhausted.