2019 April Meeting - Reactive Programming Applying Duality: The Lost Art of Denotational Semantics

The phrase Denotational Semantics is an academic term for mapping programs to mathematical objects as a way to define their meanings. This phrase is not well-known in industry but we use it here to make it clear that this presentation is a shamelss rip off of a talk by Erik Meijer of a similar title. Erik Meijer, the founder of Applied Duality, is often cited as the inventor of 'reactive', a group of frameworks which have shown up in almost every programming language. The universal applicability of Meijer’s initial reactive framework is attributed by Meijer to long-established mathematical principles such as currying, duality, and coproducts. With these few simple constructions we can understand a wide variety of interfaces in a deeper way.

As a practical example, we will cover Meijer’s derivation of Observable/Observer interfaces as duals of Iterable/Iterator interfaces. The takeaway is that every developer can apply denotational semantics to better design and implement common programs.