Functional Reactive Programming
The libraries in this subsection are as follows:
Elerea: Discrete-time FRP with a safe monadic interface
Yampa: Hybrid time FRP with first-class signal functions
Reactive-banana: Hybrid time FRP with simple semantics
FRP is handled in depth in Chapter 13, Functional Reactive Programming. There are more useful FRP libraries than the three listed here, and the balance between good semantics and performance in FRP is still taking shape.