Eve.Internal.Async

Documentation

dispatchActionAsync :: (MonadIO m, HasStates base, Typeable m, Typeable base) => IO (AppT base m ()) -> ActionT base zoomed m ()

Dispatch an action which is generated by some IO. Note that state of the application may have changed between calling dispatchActionAsync and running the resulting Action

asyncActionProvider :: (MonadIO m, HasStates base, Typeable m, Typeable base) => ((AppT base m () -> IO ()) -> IO ()) -> ActionT base zoomed m ()

This allows long-running IO processes to provide Actions to the application asyncronously.

asyncEventProvider is simpler to use, however asyncActionProvider provides more power and expressivity. When in doubt, asyncEventProvider probably meets your needs.

Don't let the type signature confuse you; it's much simpler than it seems.

Let's break it down:

When you call asyncActionProvider you pass it a function which accepts a dispatch function as an argument and then calls it with various Actions within the resulting IO. The dispatch function it is passed will have type (App () -> IO ())

Note that this function calls forkIO internally, so there's no need to do that yourself.

Here's an example:

data Timer = Timer
myTimer :: (App () -> IO ()) -> IO ()
myTimer dispatch = forever $ dispatch (myInt += 1) >> threadDelay 1000000

myInit :: App ()
myInit = asyncActionProvider myTimer