const & let

[coolaj86]

AjScript has a (mostly) traditional use of const:

1. const has a definition that's well understood:
   • a static, constant variable that can be computed at compile time \ (or "interpret time" I suppose, in a dynamic language)
2. The way that const is generally used in JavaScript leads to less readable code \ (chaining guards, ternaries, etc)

My argument is the same for always using let or var for variables as it is for always using semicolons: Easier to read, less mental load. (easier to know to put a semicolon at the end of the statement than all the ways in which a program will fail if you omit it; easier to know that a const is a constant than all the cases when it's actually mutable or variable or highly dynamic)

If you only ever use const for static constant values that can be computed at compile time you'll never end up in a situation where you're trying shoehorn a variable into a const for the sake of the using const - and you can know that when you see const that there's a real meaning behind it.

Re: https://github.com/savvi-legal/savvi.js/pull/24/files

Rationalé

Among other things...

A sane language allows assigning immutable references only once:

const naughty;
if (bad === good) {
  naughty = 'AjScript';
} else {
  naughty = 'JavaScript';
}

JavaScript doesn't, which encourages this madness:

const naughty = bad === good ? 'AjScript' : 'JavaScript'

Possible Exception

constant at initialization:

const MY_ENUM = Object.freeze({
    A: 'a',
    B: 'b',
});