A trait for fluent Durations

I dislike the pattern in some languages to create durations by multiplying constants. It feels like a concession when it cannot be expressed more nicely. There’s a tracking issue to add such constants in libstd.

How about a trait instead? (I suggested it in the tracking issue a long time ago, but it’s lost in the noise). Rust traits are awesome. They can be implemented on any other type, even primitives, without them needing to cooperate.

A trait could allow us to write 5.seconds(), or 200.milliseconds(), etc. I think this is much better. I would rather this exist instead. Maybe std::time::TimeUnits, or pick a better name, doesn’t matter which, just that it’s easy to import.