Exploring the boundaries of Ada syntax with functional-style iterators

Abstract Functional-style iterators are present in many popular languages as a way of processing data in several connected steps, in a safe and readable manner. By contrast, Ada started providing general iterators only with its 2012 revision, in a way not directly intended for sequential composition. This paper presents a functional iterators library design inspired by the standard Rust iterators and the RxAda reactive extensions. This library is used as a case study for the limitations in implementing higher-kinded types in current Ada, and how currently proposed extensions for the 202X revision might change the situation.