Functional reactive programming has no notion of event scope. A functional, declarative, reactive computation is affected as a whole by a signal, and must re-start from the beginning in some way, since it is declarative. A monad can contain the scope of the signal, so part of the computation already done, upstream, do not change when a signal is injected at some level of the computation by an active component.
A monad can decompose the computation in a chain of event handlers virtually set up by the monadic computation when it is called by the top signal, that is, when it is run for the first time. This has many applications, not only in web programmin. I present a mook-up of a comercial application:
A monad for reactive programming at SOH
