DeVault: Announcing the Hare programming language

utf8::valid() is not a great function as it stands. If the invariants actually hold, it's just a long-winded way to say "true". When in fact they don't hold, it's hard to say with confidence anything about the state of the system without an intimate knowledge of how all the parts fit together, a view that Hare's users would not have.

Attempts to inhabit states where you lack confidence in your own invariants are a bad idea. Hare should either say (like for example Go) that str is just a bunch of bytes and might not be UTF-8, and thus utf8::valid is a useful function, or, it should admit that yeah, there are a lot of APIs where it's just bytes and we need to manage that at the interface to have str work.

Rust frequently needs some of fairly big guns of parametric polymorphism to do what seems (as the user) like basic stuff. To make file open on a string work for example Rust needs AsRef<Path>. That's two types you probably never think about, and a bunch of implementation boiler plate. No actual machine code is emitted we're only satisfying the type system that, in fact, we know what we're doing. For this reason, I can see Hare won't want to go that route even though I personally prefer it.