What is Functional Programming?

Functional programming is a programming paradigm that emphasizes pure functions as the primary building blocks of software. In fact, composition plays such a central role in software development that many programming paradigms are defined by the units they use for composition:

• Object-oriented programming uses objects as the unit of composition.
• Procedural programming uses procedures or routines.
• Functional programming uses functions.

Functional programming is a declarative paradigm, meaning that code is written to describe what should be done, rather than how to do it. This results in programs that are generally easier to understand, debug, and test compared to imperative approaches. Additionally, functional code is often more concise, which reduces complexity and improves maintainability.

Key Principles of Functional Programming

• Immutability: Functional programming relies on immutable data structures. Since data cannot be changed once created, it becomes easier to reason about program behavior and avoid side effects.
• Higher-order functions: These are functions that either take other functions as arguments or return functions as results. They enable powerful abstractions and more reusable code.
• Avoiding shared mutable state: By minimizing or eliminating shared, mutable state, functional programming helps reduce bugs and makes programs easier to reason about.

Because pure functions have no side effects and always return the same output for a given input, they are inherently easier to test. As a result, functional programming often leads to better test coverage and fewer bugs in real-world applications.