John Carmack on mutable variables

> Making almost every variable const at initialization is good practice. I wish it was the default, and mutable was a keyword.

It's funny how functional programming is slowly becoming the best practice for modern code (pure functions, no side-effects), yet functional programming languages are still considered fringe tech for some reason.

If you want a language where const is the default and mutable is a keyword, try F# for starters. I switched and never looked back.

It's because you want a tasteful mix of both.

I believe Scala was pretty ahead here by building the language around local mutability with a general preference for immutable APIs, and I think this same philosophy shows up pretty strongly in Rust, aided by the borrow checker that sort of makes this locality compiler-enforced (also, interior mutability)