It has helped me see classes as a group of functions with parameters in common. The constructor helps me reduce the amount of params passed to each function. If

It has helped me see classes as a group of functions with parameters in common. The constructor helps me reduce the amount of params passed to each function. If I avoid mutating the internal state across function calls, I'm just using them as a way to group functions together (as a module would). Instantiating and then calling different methods helps me test a process at different points of the executing (testing and debugging). Inheritance helps me clean up stuff that's repeated in specific sub-problems. Mixins/modules help me in a similar way, but for stuff that's reusable in unrelated problems. I'm writing this with Ruby in mind. Seeing how OOP constructs can help me manage code that's written in a functional style has given me a middle ground: I started as 'FP is superior; use everywhere; avoid OOP languages' and now see the OOP stuff just as tools that can make it easier for me to encapsulate and reuse logic. Obv this comes with footguns: taking outside params in methods, local variables changing behaviours, indirection from inheritance/extension - the list goes on and other languages have their own. There's problems with it but as the author says, these things aren't all-or-nothing - so you can nudge the codebase in the FP/'pure' direction. "Objects are a poor man's closure.... Closures are a poor man's object."