> If you introduce a new keyword "const"
This depends on your definition of "keyword". Keywords can be absolute (which is what you assumed) and they can be contextual. Take this example:
const a = 1
That is not valid in Lua 5.3.
Therefore, Lua 5.4 could introduce a new rule for its parser/lexer: at the beginning of a statement, const followed by another identifier has a special meaning, but it has no meaning otherwise. Then, for example, the following could be valid:
const a = 1
local const = {a = 2}
const.a = a
This does make the translator more complex.
Cheers,
V.
