Short Duration constants

Proposal

Problem statement

A comment on https://github.com/rust-lang/rust/issues/57391 suggested this, and I thought it would be a great idea:

We have Duration::MILLISECOND, Duration::MICROSECOND, and Duration::NANOSECOND. These are very long names, for a concept that's usually written abbreviated.

I'd propose that we additionally add Duration::MS, Duration::US, and Duration::NS, with the same values. Or, alternatively, I propose we add Duration::MILLI, Duration::MICRO, and Duration::NANO.

Motivating examples or use cases

As with the existing constants:

time::sleep(Duration::MS);
let timeout_time = my_event.arrived_at + 100 * Duration::US;

Solution sketch

impl Duration {
    pub const MS: Duration = Duration::from_millis(1);
    pub const US: Duration = Duration::from_micros(1);
    pub const NS: Duration = Duration::from_nanos(1);
}

Alternatives

Instead of MS/US/NS, we could use MILLI/MICRO/NANO.

Links and related work

https://github.com/rust-lang/rust/issues/57391

What happens now?

This issue contains an API change proposal (or ACP) and is part of the libs-api team feature lifecycle. Once this issue is filed, the libs-api team will review open proposals as capability becomes available. Current response times do not have a clear estimate, but may be up to several months.

Possible responses

The libs team may respond in various different ways. First, the team will consider the problem (this doesn't require any concrete solution or alternatives to have been proposed):

• We think this problem seems worth solving, and the standard library might be the right place to solve it.
• We think that this probably doesn't belong in the standard library.

Second, if there's a concrete solution:

• We think this specific solution looks roughly right, approved, you or someone else should implement this. (Further review will still happen on the subsequent implementation PR.)
• We're not sure this is the right solution, and the alternatives or other materials don't give us enough information to be sure about that. Here are some questions we have that aren't answered, or rough ideas about alternatives we'd want to see discussed.

Start with this proposal and the linked rust-lang/rust#57391, then follow the libs-api feature lifecycle. The issue is done when the libs-api team resolves whether short constants belong in the standard library and selects or rejects a naming scheme; no implementation file or test is named.