Procedural programming focuses on writing procedures or methods that perform operations on data, while functional programming emphasizes the creation and application of mathematical functions.

Procedural programming is a programming paradigm that adopts a linear or top-down approach. It centers on the concept of procedure calls, where various procedures are designed to execute specific tasks. These procedures—often referred to as routines, subroutines, or functions—represent a series of computational steps that are followed to achieve a result. The primary objective of procedural programming is to decompose a programming task into a set of variables, data structures, and subroutines. However, in large procedural codebases, maintaining and updating code can become quite challenging.

Conversely, functional programming is a paradigm that constructs programs by applying and composing functions. It represents a declarative programming style that emphasizes “what” needs to be solved rather than “how” to solve it, which is the main focus of procedural programming. In functional programming, the emphasis is placed on the actions being performed rather than the methods used to perform them. Functional programming languages are built on the principles of mathematical functions and utilize conditional expressions and recursion for computation. They eschew changing state and mutable data, meaning that the output of a function solely depends on its input arguments.

In procedural programming, data and functions are treated as separate entities. In contrast, functional programming combines these concepts more closely. This distinction means that in procedural programming, a sequence of instructions directs the computer on what actions to take step-by-step. Conversely, in functional programming, computations are seen as evaluations of mathematical functions grounded in lambda calculus. For a deeper exploration of the fundamental programming constructs used in these paradigms, please refer to additional resources.