Core principles of functional programming

Functional programming is a programming paradigm that views programs as collections of mathematical functions and avoids changing data or states. While Swift is primarily a protocol-oriented language, it offers support for functional programming concepts.

Functional programming is based on several fundamental principles, and in this section, we will explore five of the most important principles, starting with immutability.

Immutability

Immutability is a key concept of functional programming that helps make code more reliable and easier to understand. Basically, immutability means that once we create a piece of data, we can’t or don’t change it. Instead of modifying the original data, we create a new version of the data with the changes.

This is different from other programming paradigms where data can be changed or modified frequently, which can lead to unexpected errors and harder-to-track bugs. By preventing...