It really depends on the language. 'const' in C works differently from 'const' in other languages (even C++, which has some great 'const' use cases that make guarantees about whether values will change, not just about the symbol binding), they both work differently than 'final'. Similar confusions with 'static'. If all you want to say is "cannot reassign this symbol", then 'val' is great and sidesteps this whole history of readability and meaning confusion.

In Rust, it does (in general) make the value immutable. Most mutations of values in Rust are done through mutably borrowing the value, which you can't do when the value is defined with `let` rather than `let mut`, the exceptions being things like `Mutex`, which gives you a value that can be mutably borrowed when you acquire the lock.