Functional Programming vs. Object Oriented Programming
Functional Programming vs. Object Oriented Programming
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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.
The older I get, the more "it depends".
This. Nothing is a silver bullet.
Not even silver bullets.
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)
Whatever it may have become in later years, Alan Kay, who is often called "The Father of Object-oriented Programming", outlined the message-passing idea as the main concept he was driving at, originally.
He also says that he probably misnamed it.
Here's a discussion in which the man himself makes a (small) appearance: https://softwareengineering.stackexchange.com/questions/46592/so-what-did-alan-kay-really-mean-by-the-term-object-oriented
JavaScript is an example of how OOP can be done without classes (before they were added to appease Java enthusiasts).
Also, I take issue with the claim that OOP is all about "objects". It's also about classes.
Depending on the language, classes are just objects too. So its still just about objects.
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.