Then you go “Can you multiply a duration with a number? No, that wôuld be stupid. Can you multiply a duration with a duration? Heck yeah!” Such an intelligent type system.
Hmm? std::time::Duration doesn’t implement Mul<Duration>, and does implement Mul<u32>, and has methods mul_f32 and mul_f64. So you can multiply a duration with a number; and you can’t multiply a duration with a duration because that would be stupid.