Transient.EVars

Documentation

newtype EVars

Constructors

EVars (IORef (Map Int [EventF]))

Instances

Typeable * EVars

data EVar a

Constructors

EVar Int (IORef (Maybe a))

Evars are event vars. writeEVar trigger the execution of all the continuations associated to the readEVar of this variable

newEVar :: TransientIO (EVar a)

creates an EVar

readEVar :: EVar a -> TransIO a

read the EVar. It only succeed when the EVar is being updated The continuation gets registered to be executed whenever the variable is updated. if readEVar is in any kind of loop, since each continuation is different, this will register again the continuation. The effect is that the continuation will be executed multiple times To avoid multiple registrations, use unsubscribe

writeEVar :: EVar t -> t -> TransIO ()

update the EVar and execute all readEVar blocks with last in - first out priority

unsubscribe :: EVar t -> TransIO ()

unsuscribe the last readEVar executed for this EVar