Formal differences don't capture how awkward something can be to use. For applied programming this matters. Maybe I can do functional programming in Java, but if it's much more verbose than Haskell and the type checker occasionally falls over then it's not a good choice.
Re:Why I Prefer Functional Programming
by AnimalMuppet on Thursday September 19, 2019 @04:49PM
(#21020606)
In what sense is Haskell a "strict superset" of OOP?
Re:Why I Prefer Functional Programming
by marcosdumay on Thursday September 19, 2019 @05:37PM
(#21020987)
In the sense that you can recreate all the usual OOP syntax and behavior on Haskell. What people only do on practice for very limited extents, because it's not very useful to import those concepts to a language aimed at dealing with pure functions.
Once you get to the scientific literature about the subject (where actual experts reside), it tends to be much more common to see the conclusions of "there isn't any formal difference between OOP and FP languages", or that in Haskell in particular "implements an strict superset of OOP".
The problem is that FP and OOP are ill-defined concepts.