Conal Elliott, inventor of Functional Reactive Programming, tells us about the birth of FRP as well as other stories from his 30+ years of functional programming experience. He shares what he considers the fundamentals of FRP (behaviors and events) and how they work in a model with continuous time. We speak about FRP practicality and efficiency, including how a continuous time model can help lead to a high performance implementation. Eventually we’re led into Denotational Design, which plays a part in the design and refinement of FRP and which Conal considers his simplest and clearest design tool.