Byte-sized functional programming: Pure functions encourage small code
Byte-sized functional programming: Pure functions encourage small code
One of the many pieces of advice for a long-term sustainable code base is to keep code small. The larger a code base is, the more effort it takes to understand all the moving parts. Your brain can only keep so much mental model of your code in it at once, and if the code you're looking at is too large then what you can fit in your own "active memory" at once then you will have an increasingly hard time understanding it.
Most useful applications tend to grow larger than what the typical human can fit in their active memory, however, so you need a way to break up your code so you can load a relevant piece into your brain at once to understand and debug it. Usually that takes the form of encapsulation, coupling, cohesion, and other common object-oriented vernacular.
But what about just a pure function?
A pure function is a function that: