Anecdotal data point of one guy's opinion, with no elaboration on reasons? Convincing. I'm talking about WHY analyzing dynamic languages is fundamentally undecidable in many cases without run time knowledge. Trying to do anything other than heuristics on some of these things is about as decidable as the halting problem. The only argument I've heard against this is you can have a hybrid environment with a REPL so your dead code is live. Ok, but you can do the same thing with static typing too.