e.g. char::is_ascii_alphabetic() was made const in 1.47, but 1.46 would already run it at compile time: https://godbolt.org/z/hWf65f
The difference is in 1.47 you can use the result to assign something that must be known at compile time.
Making them const just formally guarantees the compiler can evaluate them at compile time which makes them useful in more contexts.
`const fn` is merely an API guarantee that the function can always be evaluated at compile time if the arguments are themselves known at compile time.
> When you have a small team that write tests and a compiler that is on the boundary of interactive speed, compiler speed dominates performance.
Was the point of my answer.
Const functions let you run code to define const values. This code will be run at compile time before the const values are inlined.
For example let's say you have a constant for PI but you need 2*PI. You could do the multiplication in const context, meaning the multiplication will happen during compilation and not execution. Slowly more and more of the language is becoming usable in const context so more advanced things can be done during compile time.
Basically, const functions can be used in places regular functions can't because they are directly "run" by the compiler at compile time.
Compile-time function evaluation is also one of the features of the Jai programming language. If you can't get people to use your language, getting them to steal all your features is a good consolation prize.
It's difficult to use Jai as long as it only exists on Jonathan Blows computer, he still hasn't released it
However in this case, these are const generics, so you no longer need to use macro to generate [char;1],[char;2]...
You just write [char; N] where N is const. Compiler determines which values of N are used and generates for them an appropriate version.
Const generics still aren't stable. I believe the GP was talking about the list of new `const fn`s in the release (near the bottom of the post).