Refactoring Toward Pure Functions

Function calls to external dependency

When code has an external dependency, it rarely acts as a straight pass-through of the values of that dependency. Mostly, when a dependency is called, the response is manipulated before returning the result to the function call. The more manipulation our code does of that data, the better a candidate our code is for refactoring the logic into a pure function.

Let’s look at a visual representation of a function that calls out to a dependency and manipulate that data before returning its response.