It's less of an issue with elixir than it is with ruby or python or any other dynamic lang (or static lang) with mutability. Because of pattern matching/unifica

It's less of an issue with elixir than it is with ruby or python or any other dynamic lang (or static lang) with mutability. Because of pattern matching/unification in functions, you have a good idea what shape your data is as it's being passed around. if you still don't feel comfortable, there's always Dialyzer. Dialyzer is a static analysis tool for erlang/elixir. It's part of the standard Erlang Release and stands for DIscrepancy AnaLYZer for ERlang programs. It identifies software discrepancies such as type errors, dead code, unnecessary tests, etc., in single Erlang modules or entire (sets of) applications. Dialyzer starts from a base of correct programs and infers types; it doesn't require type annotations but uses them if they are available to provide better warnings. https://fly.io/phoenix-files/adding-dialyzer-without-the-pain/ https://fly.io/phoenix-files/adding-dialyzer-without-the-pai...