Frappé: Functional reactive programming in java

Abstract

Functional Reactive Programming (FRP) is a declarative programming model for constructing interactive applications based on a continuous model of time. FRP programs are described in terms of behaviors (continuous, time-varying, reactive values), and events (conditions that occur at discrete points in time). This paper presents Frapp´e, an implementation of FRP in the Java progamming language. The primary contribution of Frapp´e is its integration of the FRP event/behavior model with the Java Beans event/property model. At the interface level, any Java Beans component may be used as a source or sink for the FRP event and behavior combinators. This provides a mechanism for extending Frapp´e with new kinds of I/O connections and allows FRP to be used as a high-level declarative model for composing applications from Java Beans components. At the implementation level, the Java Beans event model is used internally by Frapp´e to propagate FRP events and changes to FRP behaviors. This allows Frapp´e applications to be packaged as Java Beans components for use in other applications, and yields an implementation of FRP well-suited to the requirements of event-driven applications (such as graphical user interfaces).