JavaScript Shell
This will make the language completely unusable.
clear(this);
Isn't it nice how JavaScript has such a nice function to destroy itself?
This is pretty simple, the clear
function completely empty an object. this
refers to the global object clearing out everything including constructors and functions.
Because this clears everything, doing anything, even defining a literal will throw an error, making the language completely useless: *REPL environment not required. Uses the SpiderMonkeySpiderMonkey engine (shell not browser), the original JS engine.