Combining events and behaviors
Events and behaviors are the core foundation of FRP in Reactive-banana. Behaviors can be composed via the Applicative
interface, but numerous other ways are also provided by the Reactive-banana API. Some primitives are provided:
never :: Event a unionWith :: (a -> a -> a) -> Event a -> Event a -> Event a filterE :: (a -> Bool) -> Event a -> Event a apply :: Behavior (a -> b) -> Event a -> Event b
It's apparent from the types what these functions do. unionWith
combines two events using the first argument to decide the result in case of simultaneous emits. filterE
suppresses events that don't match a predicate. apply
applies a time-varying function to events. Often apply
is encountered in its infix form, (<@>
).
A special case of apply
is replacing events with time-varying values. The (<@
) combinator can be used in this case. For example, to turn every event from etick
into a random value sampled from...