I've just finished the section 2 of the book _Crafting Interpreters_, and I wanted to upload it to github right away. Take a look at the source code. Beside the lox specification I've added:

The keyword until that is a variation of while loops (as in ruby). also

print is a function instead of a statement.

eval function that let's you eval source code in runtime.

Class methods.

I'll implement another language interpreter, this time using golang and with a syntax similar to ruby.