This article explores how functional programming principles can be integrated into object-oriented languages like C#, especially for handling structured external data, such as relational databases. It discusses how native constructs—like extension methods, delegates, events, and anonymous functions—can mimic functional paradigms to improve code predictability, composability, and maintainability. By focusing on pure functions and immutability, the article shows their importance in enabling reliable, side-effect-free data operations within database-driven environments. Practical C# examples demonstrate how functional techniques can simplify external data workflows and aid in translating logic into domain-specific languages like SQL. The discussion highlights expression trees as a vital tool for linking internal program logic with external execution platforms, paving the way for scalable and interoperable software systems.
Mariusz Postół (Mon,) studied this question.