[Sharlin]

(If you don’t own the trait either, that is. Your own traits can be implemented for foreign types.)

Rust’s approach to the Hash and Eq problem is to make them opt-in but provide a derive attribute that autoimplements them with minimal boilerplate for most types.

Also, Rust’s Hash::hash implementations don’t actually hash anything themselves, they just pass the relevant parts of the object to a Hasher passed as a parameter. This way types aren’t stuck with just a single hash implementation, and normal programmers don’t need to worry about primes and modular arithmetic.