There are optional type annotations and a tool to statically check them (dialyzer) The learning curve is a bit steep as dialyzer works on erlang terms internal

There are optional type annotations and a tool to statically check them (dialyzer) The learning curve is a bit steep as dialyzer works on erlang terms internally but we've been using it for a rather large codebase for 4+ years now and it does a consistently good job. The Elixir core team actually mentioned that they want to make improved type support a priority in the last keynotes.