Gradual typing could still keep some static guarantees if the static part were sound, e.g. you couldn't assign a dynamic-typed integer to a string-typed variabl

Gradual typing could still keep some static guarantees if the static part were sound, e.g. you couldn't assign a dynamic-typed integer to a string-typed variable without checking the type at runtime first; which TypeScript isn't. Elixir's new type system does much better here, as it determines whether a function actually guards for the right type at runtime ("strong arrows") and propagates the guarantees, or lack thereof, accordingly.