@Crell I'm guessing it's not WordPress compatible, is it? Where you are already steeped in the constraints of their language?
@worldsendless I second https://phptherightway.com/ . Note that WordPress is pretty much "PHP the wrong way" though - the way the whole thing is structured is more in line with what was common in the early 2000s, and it doesn't use fundamental concepts such as routing. I suggest avoiding WordPress whenever possible.
@Albright WordPress may have ugly code, but it is a crucial player in my job between ecosystem and open-source
@worldsendless If you're already coming from a functional language and know some PHP already, https://leanpub.com/thinking-functionally-in-php/ is a good overview of functional-think in PHP. It's not as popular, but it's definitely possible. (And I'm working on it. :-P )