Dynamic typing can forbid the latter (at runtime), but it's implementation dependent. There's a further distinction, Latent typing, which is where types are associated with values rather than variables.
But a dynamic language can have types associated with variables, and it can forbid changing those types after their types have been checked the first time.
> But a dynamic language can have types associated with variables, and it can forbid changing those types after their types have been checked the first time.
`auto` is still using static typing, and is a tool for type inference. A dynamically typed version might look equivalent but would behave differently, failing at runtime rather than compile time.
But a dynamic language can have types associated with variables, and it can forbid changing those types after their types have been checked the first time.