The practical value is that moving a computation from runtime to compile time can then be purely an optimization, rather than potentially changing its semantics. Think generated lookup tables or numeric constants. Ideally f(x) means the same thing whether evaluated by the compiler or by the generated program.
> Ideally f(x) means the same thing whether evaluated by the compiler or by the generated program.
Absolutely, that’s why I wanted to know what types of things aren’t covered yet, and that’s also why I don’t share your certainty that they won’t be resolved later.
You'd have to read the discussions the Rust community has about this to get a picture. It's complicated.
From what I understand, there is hope for sqrt but there is no consensus on transcendentals.