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Summary

Add syntax sugar for importing a module and items in that module in a single view item.

Motivation

Make use clauses more concise.

Detailed design

The mod keyword may be used in a braced list of modules in a use item to mean the prefix module for that list. For example, writing prefix::{mod, foo}; is equivalent to writing

use prefix;
use prefix::foo;

The mod keyword cannot be used outside of braces, nor can it be used inside braces which do not have a prefix path. Both of the following examples are illegal:

use module::mod;
use {mod, foo};

A programmer may write mod in a module list with only a single item. E.g., use prefix::{mod};, although this is considered poor style and may be forbidden by a lint. (The preferred version is use prefix;).

Drawbacks

Another use of the mod keyword.

We introduce a way (the only way) to have paths in use items which do not correspond with paths which can be used in the program. For example, with use foo::bar::{mod, baz}; the programmer can use foo::bar::baz in their program but not foo::bar::mod (instead foo::bar is imported).

Alternatives

Don’t do this.

Unresolved questions

N/A