[jerf]

Remarkably, a post written in generalities speaks in generalities. None of those things may be "necessary", but there sure is a lot of all the things I said, aren't there?

What you call "speaking around" I call an important thing to understand about a lot of languages: At some point, your data will be physically laid out in memory. If you don't care about performance... and I mean that as a perfectly valid choice in many situations, not a snark... it doesn't much matter how it is. But if you do, and you selected a language based on that, it matters a lot, and you have to view every type system detail through the lens of "what does it look like in memory?" if you want to understand it. The choices this class of language makes for their type systems will never fully make sense if you are not paying attention to this, and also if you gloss over the legitimate difficulties that arise for any sort of "why don't they just...?" sorts of questions.

(In particular, you really don't understand how good Rust is until you look at it through this lens, then look at just how much simultaneous power and convenience they've drawn out while never compromising on the memory issues. It's an incredible piece of work. It probably isn't "optimal" because such things don't exist in our real universe, but it probably is as close as we'll ever see for that class of langauge.)