Monkey interpreter

Implementation of a Monkey interpreter. This project is derived work from the original language developed by Thorsten Ball.

Features

Pretty much the regular monkey language, with a few customizations:

• Supports range expressions like 0..123.
• Supports variable-length arguments to functions with fn(a, ...) { } syntax.
• Supports builtin functions to turn a vararg object into an array, like fn(a, ...) { a + len(toArray(...)) }.
• Support a contains builtin that returns a boolean indicating if a Hash object contains a key.
• Closures capture the environment by value, not by reference, making it truly functional.
• Implements nicer error reporting, giving contextual information of where the error happened.
• Apart from the interpreter, it implements the bytecode VM and a transpiler to C++, which turns out to be the fastest.
• Saves the repl history using liner.