Dialyzer really gives you what you put into it. It never false-positives (by design), even while working with limited information, so if you're not writing type

Dialyzer really gives you what you put into it. It never false-positives (by design), even while working with limited information, so if you're not writing typespecs, there's only so much it can do. If, though, you make a habit of writing typespecs for everything, and defining domain-specific types rather than relying just on the primitives, it can get you surprisingly far. It'll never be as powerful as Haskell or Idris, but it's absolutely a tool all Elixir (and Erlang) developers should be using. Also, if anyone ever wants an easy way to contribute to open-source Elixir, just start running Dialyzer on popular projects. Every warning that pops up will be a bug, and often they'll be easy to fix.