Bang (!) operator

[Chriscbr]

Feature Spec

The bang operator can be used to tersely unwrap an optional value, throwing an error if it is nil. This is notably different from TypeScript's bang operator (!), which silently allows code to continue running if is undefined or null.

For example:

struct Person {
  name: str;
  age: num;
}

let person = Person.tryParseJson(req.body)!;
log("${person.name} is ${person.age} years old.");

In the example above, Person.tryParseJson returns Person? because parsing the string as Json and converting the Json to Person may fail. If it fails, the "!" indicates that the code will automatically throw an error.

foo! is syntax sugar for foo ?? throws "Unexpected nil" (tracking issue: #3858).

Use Cases

See example above

Implementation Notes

No response

Component

Language Design, Compiler

Community Notes

• Please vote by adding a 👍 reaction to the issue to help us prioritize.
• If you are interested to work on this issue, please leave a comment.
• If this issue is labeled needs-discussion, it means the spec has not been finalized yet. Please reach out on the #dev channel in the Wing Slack.

[eladb]

I think the example should use tryParseJson() no?

[Chriscbr]

Fixed - thanks

[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!

[meirdev]

I think I can implement it, is it ok to send PR?

[staycoolcall911]

@meirdev - yes, please.

The discussion around the syntax is done, so this should be good to work on. I'm removing the needs-discussion label.

We might need to refactor it a bit in the future once we work on #3858, but that shouldn't hold your work on this issue.

I assigned you on this issue so others won't work on it simultaneously. Let us know if you have any questions. Thanks!

[eladb]

This is implemented, no?

[Chriscbr]

I believe so - closing