Functional and Reactive Patterns in Idiomatically Imperative Programming Languages

Abstract: Functional and reactive programming patterns provide powerful sets of tools for dealing with complexity and scalability. These stand in stark contrast to the imperative programming patterns which permeate the industry. This report seeks to investigate the extent to which a set of common imperative programming languages can be used to implement such functional and reactive patterns, and what the implications of doing so are. This is done by implementing and using a framework based on such patterns in Java, Kotlin, Objective-C, and Swift. The results show that this is possible in all of these languages, but the extent to which this can be considered idiomatic is questionable. Upholding immutability and referential transparency is highlighted as the main source of concern in this regard.