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I think there's a huge opportunity for FP+OO... but that OO will have to be rethought from first principles (which are lacking in OO). More specifically, I thin

I think there's a huge opportunity for FP+OO... but that OO will have to be rethought from first principles (which are lacking in OO). More specifically, I think OO-style code interactions are great but that they need to be separated from ambient mutability, subtyping, subclassing, inheritance, etc. This has already happened. Ideally, good object-oriented code should always prefer immutability over mutability, should prefer interface polymorphism over inheritance polymorphism, should prefer has-a relationships (the OO version of composition) over is-a relationships (subclassing), and so on. Much of this was originally figured out a very long time ago. So the issue isn't that these standards don't exist; it's that they aren't widely understood among users of object-oriented languages. That, in turn, is because OO is so widely used by so many programmers, including a lot of people with very limited formal training in computer science, that most users of OO languages have very little exposure to any of the literature about what constitutes well-crafted object-oriented code. Certainly less so than in FP, which benefits (in this department) from the fact that it hadn't even begun to escape the ivory tower in any sort of serious way until just a few short years ago. In short, object-oriented programming is a victim of its own success. It doesn't help that the first really widespread object-oriented language wasn't particularly object-oriented, either.

jberryman 12y ago
> So the issue isn't that these standards don't exist; it's that they aren't widely understood among users of object-oriented languages. But we're talking about language design. I think enforcing constraints is much (maybe all, from a certain point of view and definition of "constraint") of what a programming language ought to do. Haskell code is principled because the language is principled, not because of conventions passed from an ivory tower. Also do you know of any languages built around those principles you mention? It sounds like studying such a language might make OO click for me a little more.
tel 12y ago
> Ideally, good object-oriented code should always prefer Really what I'm referring to is a language which outlaws instead of one that leaves it up to preference. And by outlaw I don't mean entirely, but instead a language which requires the programmer explicitly opt into these richer domains as they are needed. My understanding is that while these principles are understood as valuable, OO is generally constructed as too permissive to enforce them. In a similar story, unbounded recursion is generally "bad" in almost every part of a program---nobody likes mysteriously hanging programs---but only total languages have a formalism which allows you to profitably outlaw it. So I'm convinced there are the beginnings of the theory of objects lurking around out there even if they rarely see the light of day (really) in practice. But I also recognize that modern functional semantics grew over the last 80 years. I don't think (maybe I'm wrong) that the whole package of OO has had so long to mature.

jberryman 12y ago

> So the issue isn't that these standards don't exist; it's that they aren't widely understood among users of object-oriented languages. But we're talking about language design. I think enforcing constraints is much (maybe all, from a certain point of view and definition of "constraint") of what a programming language ought to do. Haskell code is principled because the language is principled, not because of conventions passed from an ivory tower. Also do you know of any languages built around those principles you mention? It sounds like studying such a language might make OO click for me a little more.

tel 12y ago

> Ideally, good object-oriented code should always prefer Really what I'm referring to is a language which outlaws instead of one that leaves it up to preference. And by outlaw I don't mean entirely, but instead a language which requires the programmer explicitly opt into these richer domains as they are needed. My understanding is that while these principles are understood as valuable, OO is generally constructed as too permissive to enforce them. In a similar story, unbounded recursion is generally "bad" in almost every part of a program---nobody likes mysteriously hanging programs---but only total languages have a formalism which allows you to profitably outlaw it. So I'm convinced there are the beginnings of the theory of objects lurking around out there even if they rarely see the light of day (really) in practice. But I also recognize that modern functional semantics grew over the last 80 years. I don't think (maybe I'm wrong) that the whole package of OO has had so long to mature.