: Once you create a piece of data, you never change it. If you need a modified version, you create a whole new copy with the changes.
: A function is "pure" if it always gives the same output for the same input and has no side effects (it doesn't change anything outside itself, like updating a database). Functional Programming For Dummies
Functional programming (FP) is a style of coding where you treat software as a series of mathematical functions rather than a list of instructions. Instead of telling the computer to do something step-by-step, you describe what you want to happen. The Core Pillars of Functional Programming : Once you create a piece of data, you never change it
If you want to write code like a functional programmer, you need to follow these basic rules: Functional programming (FP) is a style of coding