[wtetzner]

> I am personally ok with and support having any large scale, long term project require multiple versions of the compiler to build.

Or even better, have every compiler support all versions of the language. It obviously requires some careful architecting to keep it maintainable, but that's better than every user of the compiler having to sort out versioning issues themselves.

Edit: I've re-read your comment, and I can't tell if we're in agreement or not :)

[sitkack]

> have every compiler support all versions of the language

If having an interface that looks like the compiler do this, I am fine with it, but a single codebase ... not so sure. Large systems collapse under their own weight, having to support all versions when the current-4 already supports it seems kinda ridiculous.

[wtetzner]

Well, hopefully the changes between versions aren't too big, because at some point it doesn't make sense to consider them to be the same language.

The idea is that each version would still be translated into a common internal representation pretty early on after parsing, so it would almost be like supporting multiple versioned mime-types in a REST API.

And it's probably harder to do with languages that already exist, but if the spec is defined from the start with versioning in mind, then it might not be so difficult.

[sitkack]

These are the things that I think Rust should really be concentrating on. How to make a vibrant language that can support 10-20-50 year codebases and still remain fresh.