Evolution of Functional UI Paradigms

Functional paradigms for user-interface (UI) programming have undergone significant evolution, from early stream-based approaches, monad-based toolkits mimicking OO practice to modern model-view-update frameworks. Changing from the classic Model-View-Controller pattern to functional approaches drastically reduces coupling and improves maintainability and testability. On the other hand, achieving good modularity with functional approaches is an ongoing challenge. This paper traces the evolution of functional UI toolkits along with the architectural implications of their designs---including two of our own---summarizes the current state of the art and discusses remaining issues.