I use Swift for work. The compiler tell you this. If a mutable variable is never mutated it suggests making it non-mutable. And vice versa.

Yup, it's pretty great. You get into the habit of suspiciously eyeing every variable that's not a constant.

As will Typescript, at least using Biome to lint it does.

My very minor complaint about TypeScript is you use to use `const` which is 2 additional letters.

Seriously though, I do find it slightly difficult to reason about `const` vars in TypeScript because while a `const` variable cannot be reassigned, the value it references can still be mutated. I think TypeScript would benefit from more non-mutable values types... (I know there are some)

Swift has the same problem, in theory, but it's very easy to use a non-mutable value types in Swift (`struct`) so it's mitigated a bit.