Relative to Ruby it has more upfront checking of some things. In Elixir, calling a function that doesn't exist or with the wrong number of arguments is somethin

Relative to Ruby it has more upfront checking of some things. In Elixir, calling a function that doesn't exist or with the wrong number of arguments is something that will error out at compile-time; with Ruby, you don't find out until you run the code with the bad call. I agree, though, that compared to Haskell and Rust it doesn't give you much. Dialyzer is (intentionally) a fail-open checker that doesn't allow expressing generics; I've had a rough time getting it to tell me my code is wrong. Credo is (intentionally) just a style linter. "Just let it crash" isn't useful when you're talking about code that is going to break because of its structural incoherence (a class of errors type-checker are good at catching), and not because of transient errors in external dependencies.