Functions don't return... equals goto.
Everything must be done by side effects... all variables are global.
Global state mutation is inheritance... no grok.
Every call is non-blocking and spawns a new thread... atomic bomb for junior software engineers.
??? ... shorting the stock of the company that adopts this.
I fundamentally disagree with the idea that these are competing strategies.
Just like walking doesn't really compete, like at all, with flying in an aircraft, Functional and Object Oriented Programming are at their best when you use whichever approach makes sense for a given situation and in any reasonably complex software that means your code should be full of both.
OOP is really good at the high level structure of your software as well as efficiently storing data. FP is really good at business logic and algorithms.
Also, I take issue with the claim that OOP is all about "objects". It's also about classes. In fact I'd argue classes are more important than objects.
Object-oriented design is about message-passing; messages are more important than objects. Classes are completely irrelevant -- there's an entire branch of object-oriented language design without classes!
there’s an entire branch of object-oriented language design without classes!
That's not OOP anymore. There's definitely a lot of OOP code out there (especially in the Java world) that goes way too far with inheritance and class structures, and good OOP code relies a lot less on classes - but they are still used and a critical component of the style of programming.
Object-oriented design is about message-passing;
I'd argue that's an implementation detail rather than part of OOP. Also it's rarely used in modern OOP languages because it's just too slow*. Unfortunately when you take it away some patterns are lost, but the trade off is generally worth it.
(* when I used to work in Objective-C, message sending was often slower than all of the rest of my code combined and in tight loops I'd often rewrite my OOP code as procedural C code in order to have acceptable performance. Never need to do that in Swift, which doesn't do messages)
Just like walking doesn't really compete, like at all, with flying in an aircraft, Functional and Object Oriented Programming are at their best when you use whichever approach makes sense for a given situation and in any reasonably complex software that means your code should be full of both.
I'm not really sure sure that's true.
In FP languages like Haskell, you get tools like algebraic data types, typeclasses, and pattern matching.
FP is really opposed to imperative programming, while objects are opposed to algebraic data types.
You can write OO code that's 100% fully functional, and you can write code in Haskell or rust where you barely notice you never once used an object.
Yeah, OO and FP aren't really opposed. FP is opposed to imperative programming.
That said, most FP languages give you a slightly different set of tools to use. Algebraic data types and typeclasses are really, really nice.
Honestly, working in Haskell or rust, you don't really miss the fact that you have to jump through hoops to get traditional OO objects. There's just not really many cases where you need them.
Functional is so sexy and I try to use it where I can but I work in a real time environment where the microsecond price of copying immutable data is just too damn high. Still it's useful in places that aren't time critical, especially if the problem is complex.