Side-Effects

The Foundation of Predictable Code

In the first post, we explored immutability. In the second post, we saw how functions are values. Now we’ll tackle a concept that ties them together: pure functions.

Pure functions are the building blocks of functional programming. They’re predictable, testable, and easy to reason about. But real applications need side effects - saving to databases, making HTTP requests, printing to the console. The key is knowing how to write pure functions and where to isolate side effects.