Share / export constants between Wing files and libraries

[Chriscbr]

Feature Spec

Wing now supports bringing specifying constants as shared/public by a module (Wing file), and then bringing them into other Wing modules.

Use Cases

Reusing information (supporting DRY). Example:

// constants.w
pub let DATA = "Hello world!";

// main.w
bring "./constants.w" as constants;
bring cloud;

let bucket = new cloud.Bucket();
bucket.addObject("data.txt", constants.DATA);

Alternative syntax suggestions welcome.

Implementation Notes

The design reason to only support sharing constants (and not any values) is to avoid the semantic ambiguities that arise when sharing mutable values across module boundaries:

// file1.w
let pub a = MutArray<num>[1, 2, 3];

// file2.w
bring "./file1.w" as stuff;
stuff.a.push(4);

// file3.w
bring "./file1.w" as stuff;
stuff.a.push(5); // is the array [1, 2, 3, 4, 5] or [1, 2, 3, 5, 4] or [1, 2, 3, 5] ?

In the initial version, a list of types we can support as constants are:

• num
• str
• bool
• duration
• datetime
• Json
• Array<T>, Map<T>, or Set<T> where T is a valid constant type
• T? where T is a valid constant type
• any enum value
• any struct whose fields are all valid constant types

Free floating functions and may also be reasonable to share across module boundaries in the future.

Component

Language Design, Compiler

Community Notes

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[github-actions]

Hi,

This issue hasn't seen activity in 60 days. Therefore, we are marking this issue as stale for now. It will be closed after 7 days.
Feel free to re-open this issue when there's an update or relevant information to be added.
Thanks!

[github-actions]

Hi,

This issue hasn't seen activity in 90 days. Therefore, we are marking this issue as stale for now. It will be closed after 7 days.
Feel free to re-open this issue when there's an update or relevant information to be added.
Thanks!

[github-actions]

Hi,

This issue hasn't seen activity in 90 days. Therefore, we are marking this issue as stale for now. It will be closed after 7 days.
Feel free to re-open this issue when there's an update or relevant information to be added.
Thanks!

[Chriscbr]

@boyney123 mentioned that sharing functions should also be pretty safe to also define as constants under these rules.