Do note that when it comes to evaluating binary expressions, we are
asserting in multiple contexts that the values we're operating on are
numbers, we should probably handle other value types to be more tolerant
in the future, since for example, adding a number and a string, in
which case the number is converted to a string implicitly which is then
concatenated, although ugly, is valid javascript.
If statements execute a certain action or an alternative one depending
on whether the tested condition is true or false, this commit helps
establish basic control flow capabilities in the AST.
I always tell people to start building things by working on the thing
that seems the most interesting right now. The most interesting thing
here was an AST + simple interpreter, so that's where we start!
There is no lexer or parser yet, we build an AST directly and then
execute it in the interpreter, producing a return value.
This seems like the start of something interesting. :^)
