Looks like Rust is https://doc.rust-lang.org/stable/std/keyword.let.html

Erlang doesn't allow variable reassignment. Elixir apparently does, but I've never played with it.

typescript handles that well already

That's probably because reassignment is already covered by using `const`.

Of course, it doesn't help that the immutable modifier for Swift is `let`. But also, in Swift, if you assign a list via `let`, the list is also immutable.

If you need the index, you can use .keys() or .entries() on the iterable, e.g.

    for (const [index, value] of ["a", "b", "c", "d", "e"].entries()) {
      console.log(index, value);
    }

Or forEach, or map. Basically, use a higher level language. The traditional for loop tells an interpreter "how" to do things, but unless you need the low level performance, it's better to tell it "what", that is, use more functional programming constructs. This is also the way to go for immutable variables, generally speaking.