Principles of functional programming
FP is a way of thinking, a specific style of constructing and building programs. Having an FP language helps a lot in terms of syntax, but at the end of the day, it's all about ideas and developer mindset. FP favors disciplined state management and immutability in a declarative programming way rather than the imperative programming mostly used by OOP languages such as Java, Python, and Ruby.
FP has roots in math back to Lambda calculus - a formal system developed in the 1930s. Lambda calculus is a mathematical abstraction and not a programming language, but it is easy to see its concepts in programming languages nowadays.
Imperative programming uses statements to change the program state. In other words, this means you give commands to the program to perform actions. This way of thinking describes a sequence of steps on how the program needs to operate. What you need to keep in mind is the kind of style focus on how FP works in a different way, focusing on what the program should accomplish without telling the program how to do it. When you are coding in FP, you tend to use fewer variables, for loops, and IFS, and write more functions and make function composition.
The following are the CORE principles of FP:
- • Immutability
- • Disciplined state
- • Pure functions and no side effects/disciplined states
- • First class functions and high order functions
- • Type systems
- • Referential transparency
Let's understand these principles in detail.
