A minimalistic FRP library.
Elerea (Eventless reactivity) is a tiny discrete time FRP implementation without the notion of event-based switching and sampling, with first-class signals (time-varying values). Reactivity is provided through various higher-order constructs that also allow the user to work with arbitrary time-varying structures containing live signals. Signals have precise and simple denotational semantics.
Stateful signals can be safely generated at any time through a monadic interface, while stateless combinators can be used in a purely applicative style. Elerea signals can be defined recursively, and external input is trivial to attach. The library comes in two major variants:
Simple: signals are plain discrete streams isomorphic to functions over natural numbers;
Param: adds a globally accessible input signal for convenience;
This is a minimal library that defines only some basic primitives, and you are advised to install elerea-examples as well to get an idea how to build non-trivial systems with it. The examples are separated in order to minimise the dependencies of the core library. The dow package contains a full game built on top of the simple variant.
The basic idea of the implementation is described in the WFLP 2010 paper Efficient and Compositional Higher-Order Streams (http://sgate.emt.bme.hu/documents/patai/publications/PataiWFLP2010.pdf).
Additional contributions: Takano Akio, Mitsutoshi Aoe