John Carmack on mutable variables

Proposing making immutable by default in C or C++ doesn't make sense due to backwards compatibility reasons. New languages like Rust have easier time making better choices with immutable by default.

cpp2/cfront could plausibly do this, right? Except he doesn't want to:

https://github.com/hsutter/cppfront/wiki/Design-note%3A-cons...

Well, if they are willing to break backwards compatibility, a lot of things can be improved, including this.

They could just add a "use immutable;" directive that you place at the top of your file.

C# does this with the null hole. I wish more languages would take a versioning approach to defaults at the file-level.

Could be a compiler flag. -const-by-default. Would probably mean you need to scatter mutable across the codebase to get it to compile, but I expect some people would like to have every local annotated as const or mutable.

Maybe the new C++ profiles that are supposedly going to make C++ a safe language could do it.