@hackage elerea2.1.0

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.

Stateful signals can be safely generated at any time through a specialised monad, 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 four major variants:

• Simple: signals are plain discrete streams isomorphic to functions over natural numbers;

• Param: adds a globally accessible input signal for convenience;

• Clocked: adds the ability to freeze whole subnetworks at will;

• Delayed: attempts to resolve instantaneous dependency cycles (i.e. cycles without a delay); this variant is likely to be deprecated in the near future.

The first three variants come with precise denotational semantics.

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.