I agree, this looks terrible. It seems every discussion about static vs. dynamic typing on HN ends with the following realizations, spread over multiple comments:

- its hard to safely refacture without static types (and the help of the IDE that often comes with it)

- dynamic languages must compensate the missing type checking support from the compiler with additional unit tests, negating the productivity gains

Sometimes it would be nice to have both worlds in the same language, but the way Clojure does it does't appeal to me at all.