Sometimes I’ve wondered if versioned types might be a help in bringing coexistence to a typed setup, and if this is part of where the benefits of a service oriented architecture come from. But given how versioning snarls can play out in dependency management I expect this idea has some tradeoffs in the best case.
Not the most elegant mechanism, but it should be accessible to imagine an implementation via inheritance hierarchies even for a static manifestly typed language. Class "Person4.1" inherits from class "Person4" inherits from class "Person2" inherits from "Person". Probably there's a better way (and one could argue that a design where knowing the version of the class/object matters isn't a well-encapsulated design, which could have something to do with why duck typing often works out better than expected in OO systems).
I think my question is what would you be doing here that doesn't boil down to "has these properties/methods, I'll accept"?
I think this is a lot easier if you exclude the "methods" in my quote there. Since those almost certainly have the same general contract that would spread across things.
