Module

Control.Coroutine.Aff

Package: purescript-aff-coroutines
Repository: purescript-contrib/purescript-aff-coroutines

This module defines functions for creating coroutines on top of the Aff monad.

The Aff monad only supports actions which return a single value, asynchronously, so this module provides a principled way to deal with asynchronous streams of values, and asynchronous consumers of streamed data.

#produce Source

produce :: forall eff r a. ((Either a r -> Eff (avar :: AVAR | eff) Unit) -> Eff (avar :: AVAR | eff) Unit) -> Producer a (Aff (avar :: AVAR | eff)) r

Create a Producer using an asynchronous callback.

The callback should provide zero or more values of type a, which will be emitted by the Producer, terminated by an optional value of type r. No values should be provided after a value of type r has been provided.

For example:

produce \emit -> do
  log "Working..."
  emit (Left "progress")
  log "Done!"
  emit (Right "finished")

#produce' Source

produce' :: forall eff m r a. MonadAff (avar :: AVAR | eff) m => ((Either a r -> Eff (avar :: AVAR | eff) Unit) -> Eff (avar :: AVAR | eff) Unit) -> Producer a m r

A version of produce that creates a Producer with an underlying MonadAff, rather than Aff specifically.

#produceAff Source

produceAff :: forall eff r a. ((Either a r -> Aff (avar :: AVAR | eff) Unit) -> Aff (avar :: AVAR | eff) Unit) -> Producer a (Aff (avar :: AVAR | eff)) r

A variant of produce where the setup and callback functions use the Aff monad. This can be helpful in certain cases.

For example:

produceAff \emit -> do
  later' 1000 $ emit $ Left "progress"
  later' 1000 $ emit $ Right "finished"

Modules: Control.Coroutine.Aff