`const` as an alternative for `let`

[Gusarich]

There are already static constants in Tact that can be declared outside of functions and receivers, but what about the possibility of defining constants within function bodies to enhance code?

These const definitions would work almost identically to let statements, with the only difference being that such variables would be protected from overwriting and changing.

[anton-trunov]

I like the idea

[Gusarich]

Same can probably be applied to function arguments. Example:

fun someFunction(x: Int, const y: Int) {
    // x here is changable, y is not
    x += y; // works
    y += 1; // doesn't
}

[byakuren-hijiri]

The readOnlyVariables lint in Misti could advice developers to replace let with const if the variable is never written.