No error for missing property

[osamimi]

The LSP in vscode doesn't show an error for a missing property whereas the CLI does:

[HT154]

This one is intended behavior. In Pkl it is valid to create and use objects with required properties missing as long as those properties are defined when a value is rendered. Here's an example:

class Schema {
  missing: String
  num: Int
}

local base: Schema = new {
  missing = "nope"
  // num is not defined here, but this value is never rendered so this isn't an error
}

record: Schema = (base) {
  num = 2
  // when this is rendered all required properties are set
}

It's worth noting that the LSP does not evaluate code, it only does static analysis. Therefore, in your example it cannot know that this module will even be evaluated (instead of being amended/imported elsewhere), Record will indeed be rendered, or that Record won't be amended elsewhere to provide a value for missing.

[osamimi]

Thanks for the quick response.
I am looking for equivalent functionality to JSON schema ‘required’ fields. So I guess this is not possible with pkl?
From the perspective of making sure a user is supplying a valid ‘config’ to the program, the early feedback from the LSP is very desirable.

[HT154]

There is currently no way to enforce that a particular property is set where a class is first instantiated. That's theoretically possible, but it would be a change to the language itself and I'm not sure we're looking to pursue that.

Indeed, it would be great if tools like the LSP could tell you when properties are missing, With JSON schema, the input is a static format so that kind of validation is straightforward. That's difficult-to-impossible in Pkl because of its dynamism. Flipped around: it would be pretty annoying if the editor annotated warnings or errors in locations where you know the value won't be rendered without further amending!

[osamimi]

I see the challenge. Perhaps it requires a ‘final’ keyword in the language where the user explicitly tags an object as intended to be complete and compliant with the class/schema.