why does

concrete_time

need to exist?

In rust, a duration is designed to hide its implementation details from you. Among other things, that means you can’t serialize it. concrete_time gives you a

Duration

that exposes its implementation details so it can be serialized.

concrete_time::Duration

implements

From

and

Into

for the standard duration so you’re encouraged to use that in most places and only use the concrete_time one if you need the serialization.