Becoming a professional Haskell and Erlang developer really shifted my view on OOP (let OOP denote class based OOP as found in Java or C++). In my view, OOP is prove a poor model for computation, and the result has been that OO code is almost always significantly more complex and error prone than an equivalent computation written in a concurrent, functional, or structured paradigm. Recent trends in language design (see Rust, Go, Elixir) also seem to be abandoning OOP in favor of other models as well.
OOP provides competing ways of abstracting behavior that in Haskell we can model with type parameters and constraints. Objects are not truly encapsulated in the way Erlang processes are and a poor fit for SMP. Objects also pathologically hide data in attempt to manage mutability, making it impossible to reason about the memory layout of the program.
All in all, OOP is a toolkit for building bad abstractions: abstractions that do not easily model computation, that hide data, and has tended to create overly complex solutions to problems that are often full of errors that a language focused more on type expressivity could catch at compile time.
OOP provides competing ways of abstracting behavior that in Haskell we can model with type parameters and constraints. Objects are not truly encapsulated in the way Erlang processes are and a poor fit for SMP. Objects also pathologically hide data in attempt to manage mutability, making it impossible to reason about the memory layout of the program.
All in all, OOP is a toolkit for building bad abstractions: abstractions that do not easily model computation, that hide data, and has tended to create overly complex solutions to problems that are often full of errors that a language focused more on type expressivity could catch at compile time.