For me the example printing `1` makes sense because I think `let` as being something immutable, so I wouldn't expect `setv` to mutate that variable (would expect either a compiler error or the introduction of a new local variable).

But maybe it is because I am familiar with Clojure (where `setv` or equivalents doesn't exist) and not other Lisps.

This would be the equivalent Clojure code anyway:

  user=> (let [a 1] (defn foo [] (def a 2)) (foo) (println a))
  1
  nil

So yeah, makes sense for me. But can understand why some other people would expect the other way though.