Which programming paradigm emphasizes the use of functions as fundamental building blocks?

The programming paradigm that emphasizes the use of functions as the fundamental building blocks is Functional Programming. In this paradigm, computation is treated as the evaluation of mathematical functions and avoids changing-state and mutable data. Functions in functional programming are first-class citizens, meaning they can be passed as arguments, returned from other functions, and assigned to variables. This promotes a focus on composing functions to build more complex operations, and leads to clearer and more predictable code.

By leveraging pure functions, functional programming encourages immutability, which contributes to easier reasoning about code behavior, especially in concurrent programming environments. Additionally, this paradigm supports higher-order functions, enabling developers to create more abstract and reusable components.

While procedural programming does use functions, it focuses on the step-by-step logic of procedures or routines as the primary means to structure code, not elevating functions to the same conceptual level as in functional programming. Object-oriented programming emphasizes objects and classes, centering around data encapsulation and inheritance rather than just functions. Data-driven programming focuses on the data itself as the primary driver of program behavior, which does not align with the function-centric approach of functional programming.