“Even though I'm never expecting my game to read an empty string in from an s-expression, I didn't want that to be a limitation of the parser.”

This thing is never going to ship. Coming from someone who has written an IDE and wasted a bunch of time on the parser because it was the cool theoretical portion.

That’s fine, I assume learning rather than shipping is the goal here. A fine goal it is.

By the way, the problem is NOT that he wrote his own parser and other homemade tools. This is actually a great thing to do —third party tools usually end up being more trouble than they’re worth. The problem is that he’s ratholing on tiny details that don’t matter.