Module Control.Concurrent

Support for concurrency.

Concurrency in Frege comes in 2 flavors. The first is through Threads, which are, unlike in Haskell, OS threads.

The second possibility is to use a thread pool and an executor service one can submit tasks to. But note that blocking asynchronous tasks, unlike Haskell green threads, will block an OS thread on blocking actions.

Imports

import Java.util.Concurrent as C
import frege.Prelude as Prelude
import Prelude.PreludeArrays as PreludeArrays
import Prelude.PreludeBase as PreludeBase
import Prelude.PreludeDecimal as PreludeDecimal
import Prelude.PreludeIO as PreludeIO
import Prelude.PreludeList as PreludeList
import Prelude.PreludeMonad as PreludeMonad
import Prelude.PreludeText as PreludeText
import Java.util.Regex as Regexp

Table of Content

Definitions

data MVar a

newEmptyMVar ∷ IO (MVar 𝖆)

newMVar ∷ 𝖆 → IO (MVar 𝖆)

takeMVar ∷ MVar 𝖆 → IO 𝖆

putMVar ∷ MVar 𝖆 → 𝖆 → IO ()

tryTakeMVar ∷ MVar 𝖆 → IO (Maybe 𝖆)

tryPutMVar ∷ MVar 𝖆 → 𝖆 → IO Bool

forkOS ∷ IO () → STMutable RealWorld Thread

forkIO ∷ IO () → IO ()

shutdown ∷ IO ()

async ∷ IO a → IO (MVar (Exception | a))
Functions and Values by Type

Definitions

data MVar a

A thread safe, shared variable, that is either full or empty.

Technically, this is just a BlockingQueue restricted to length 1.

Constructors

private MV (MutableIO (BlockingQueue a))

Member Functions

new ∷ 𝖆 → IO (MVar 𝖆): create a MVar filled with a value
newEmpty ∷ IO (MVar 𝖆): create an empty MVar
offer ∷ MVar 𝖆 → 𝖆 → IO Bool: put a value in a MVar, returns false if already full.
poll ∷ MVar 𝖆 → IO (Maybe 𝖆): get the value from a MVar, return Maybe.Nothing when empty
put ∷ MVar 𝖆 → 𝖆 → IO (): put a value in a MVar, blocks if full
take ∷ MVar 𝖆 → IO 𝖆: take a value from a MVar, blocks if empty

newEmptyMVar ∷ IO (MVar 𝖆)