The proposal doesn't seem to take into account the versioning of the included modules.

> import { Date } from "std:Date";

> import { Date } from "std:Date+2.1.6-alpha.1";

Which version is the first line going to include? Latest? First?

importmap for backward compatibility / polyfills is very neat though.

I would love to see lowdash/underscore included as a standard library.