functional core, imperative shell

order process part 2: refining the domain model and building an anti-corruption layer

Last time, we created a testable implementation of a simple function, that takes an order, computes some values like net / gross totals and tax, and returns the result so we can print it. Here is part 1 if you're interested. As a refresher, here is what that program

php

order process part 1: Increasing purity and testability

In this article I want to show you how to increase function purity, modularity and testability in inherently impure programs, based on a realistic code example. 🤠The following code snippets are not necessarily best practices. Each snippet is supposed to highlight one specific characteristic, without mixing in too many concepts