RxAda: An Ada implementation of the ReactiveX API

Abstract

The ReactiveX API, also known as the Reactive Extensions in the .NET world, is a recently popularized reactive programming framework for asynchronous, event-based, multi-threaded programming. Presented by its proponents as a solid tool for applications requiring a simple yet powerful approach to event-driven systems, it has seen favorable adoption in many popular languages. Although Ada has been long-favored by powerful tasking capabilities that reduce the need for additional multithreading support, the reactive approach has properties that are wellsuited to the safety and maintainability culture predominant in the Ada world, such as complexity reduction, race-condition and deadlock avoidance, and enhanced maintainability by means of concise and well-defined information flows. This work presents the design for a ReactiveX Ada implementation that aims to balance desirable library properties such as compile-time checks, reasonable user-required generic instantiations, and a shallow learning curve for both library clients and maintainers. The Ada programmer can henceforth benefit from the abundant documentation existing for the language-agnostic ReactiveX approach without stepping out of the Ada tool chain.