Documentation

Convenience alias for the consumer effect.

Interprets UninterruptipleMask, Mask and Race in terms of Final IO and runs the entire rest of the stack.

Convenience alias.

Abstracts an MVar.

For documentation on the constructors, see the module Polysemy.Conc.Effect.Sync.

import Polysemy.Conc (Sync)
import qualified Polysemy.Conc.Effect.Sync as Sync

prog :: Member (Sync Int) r => Sem r Int
prog = do
  Sync.putTry 5
  Sync.takeBlock

Create a new scope for Events, causing the nested program to get its own copy of the event stream. To be used with interpretEventsChan.

Consume one event emitted by Events.

Publish one event.

An event publisher that can be consumed from multiple threads.

The scoped masking effect.

The scoped uninterruptible masking effect.

Constructor for Scoped, taking a nested program and transforming all instances of effect to Scoped resource effect.

Scoped transforms a program so that effect is associated with a resource within that program. This requires the interpreter for effect to be parameterized by resource and constructed for every program using Scoped separately.

An application for this is Events, in which each program using the effect Consume is interpreted with its own copy of the event channel; or a database transaction, in which a transaction handle is created for the wrapped program and passed to the interpreter for the database effect.

Resource creation is performed by the function passed to runScoped.

The constructors are not intended to be used directly; the smart constructor scoped is used like a local interpreter for effect.

Abstract the concept of running two programs concurrently, aborting the other when one terminates. Timeout is a simpler variant, where one thread just sleeps for a given interval.

Abstracts queues like TBQueue.

For documentation on the constructors, see the module Polysemy.Conc.Data.Queue.

import Polysemy.Conc (Queue, QueueResult)
import Polysemy.Conc.Effect.Queue as Queue

prog :: Member (Queue Int) r => Sem r (QueueResult Int)
prog = do
  Queue.write 5
  Queue.write 10
  Queue.read >>= \case
    QueueResult.Success i -> fmap (i +) <$> Queue.read
    r -> pure r

The interrupt handler effect allows three kinds of interaction for interrupt signals:

• Execute a callback when a signal is received
• Block a thread until a signal is received
• Kill a thread when a signal is received

For documentation on the constructors, see the module Polysemy.Conc.Effect.Interrupt.

import qualified Polysemy.Conc.Effect.Interrupt as Interrupt

prog = do
  Interrupt.register "task 1" (putStrLn "interrupted")
  Interrupt.killOnQuit $ forever do
   doSomeWork

Encodes failure reasons for queues.

For documentation on the constructors, see the module Polysemy.Conc.Data.QueueResult.

import qualified Polysemy.Conc.Data.QueueResult as QueueResult

Structural logs, used as a backend for the simpler Text log effect, Log.

Can also be used on its own, or reinterpreted into an effect like those from co-log or di.

The default high-level effect for simple text messages. To be used with the severity constructors:

import qualified Polysemy.Log as Log

prog = do
  Log.debug "debugging…"
  Log.warn "warning!"

Interpreters should preprocess and relay the message to DataLog.

Types that represent an amount of time that can be converted to each other. The methods are internal, the API function is convert.

The Time effect.