[keithnz]

I think this is more based on the early methodology advice for developing OO software. But the methodology is independent of the constructs (though often limited by it).

In practice these days often the most effective way when developing OO code is working the "proofs" till you have a set of classes.

Also, some people go for very FP inspired OO code.

[codr4life]

Those are clearly exceptions to the rule, though. You can write sort of Haskell in any language, OOP is still bullshit.