[klabb3]

I was gonna say that's possible in Rust and also isn't a big problem but the more I think about it the more this comes up.

First, languages where a compiler plug-in or linter do this don't really count, because you can't extend it and they rely on specific tools. Even Rust, which has relatively good meta-programming, is very cumbersome to use. Writing proc macros is known as an archaic skill that – even though it is technically also in Rust (which is nice) – involves heavy manipulation of ASTs and has numerous pitfalls. It would be better to leave the ASTs for compiler folks if possible.

It get the sense that these features can be really useful for deserialization, which is a very common use-case in regular software development. Even where it's safe, like in Rust, deserialization is prone to logic errors and often requires lots of boilerplate (unless you use an existing library but then you must rely on unintelligible proc macro wizardry).

[valenterry]

It's not possible in Rust. Yes, you can write a macro for it or use the existing one, but now you get all the disadvantages of macros.

For instance, you cannot (to my knowledge) manipulate a macro with another macro. You can't use a macro and feed it with the format macro to get another macro. With types you can do that (obviously).