[ericn]

I have a question. With the backtracking parser, does this mean that you can rewrite parse-number like this? :

(def parse-number (domonad [sign (optional parse-sign "+") [type digits] (choice parse-integer parse-float) _ eof] [type (apply str (cons sign digits))])))

The fact that you can fail on the eof and backtrack into the choice (if it is possible) is the main advantage. It lets you lay out your parser in a logical way.