4 ms·

Sure, that fixes some problems, but I don't understand how that would solve the first example listed above. Can you explain how the compiler would prevent this

• pcwalton 11y ago
  That is a theoretical problem, yes. In practice I've never seen it be an issue, because (a) global state is frowned upon and (b) packages that depend on each other so tightly tend to have dependencies at the type level, making the probability that such errors slip past the compiler very low. To expand on (b), suppose that packages A and B depend on a shared queue managed by package C, as in your example. Because A and B have such tightly coupled logic, chances are that some package--either one of A and B, or some other package that depends on A and B--will have code that expects a type from "A's C" to be equivalent to a type from "B's C". At that point the code will fail to compile, and the programmer will fix the problem before it ever hits production. (Fixing this is easy because you can just inspect the lockfile to find all the crate versions in use.) Basically, static typing makes it such that, while the problem exists in theory, in practice its probability is so low as to not be a concern.