Force yaml (single) value output to have (single) quotes

[StefMa]

I want to have the following output:

schedule:
- cron: '* /10 * * *'
- cron: '5 4 * * *'

This is just a Listing<Mapping<String, String>>.

schedule: Listing<Mapping<String, String>> = new {
  Map("cron", "*/10 * * * *").toMapping()
  Map("cron", "5 4 * * *").toMapping()
}

You can also check this out in the pkl-playground:
https://pkl-playground.vercel.app/?share=canal-throw-building

But unfortunately the output is the following:

schedule:
- cron: '*/10 * * *'
- cron: 5 4 * * *

Notice the missing single quotes in the second cron list item

It seems that the YamlRenderer determinate if they will wrap it into quotes depending on the first char.
For me it looks like the rule of "if its a special char use single quotes, otherwise not".

While this might be (I'm not 100% sure with that 😁 ) technically correct, I still want to force wrapping it into quotes.
I tested out different things* but don't get it to work.. Can someone help me here?! 🙏

Test cases:

• Using "'5 4 * * *'" results in '''5 4 * * *'''
• Using "\'5 4 * * *\'" results in an error
• Using "\\'5 4 * * *\\'" results in \'5 4 * * *\'
• Wrapping into string literal (""") produces the same outputs, so they don't change anything ☝️

[translatenix]

YAML can be formatted in many different ways. I don’t think YamlRenderer gives users full control over the chosen syntax.

[bioball]

Render directives are an escape hatch to get the renderer to do what you want.

Here's an example: this combines a render directive with an output converter to turn all strings into JSON strings, which is still valid YAML (YAML accepts JSON strings):

cron = "* * * * *"

local jsonRenderer = new JsonRenderer {}

output {
  renderer = new YamlRenderer {
    converters {
      [String] = (it) -> new RenderDirective { text = " " + jsonRenderer.renderValue(it) }
    }
  }
}

This produces:

cron: "* * * * *"

It'll be more work to produce strings with single quotes. If your goal is to have consistent looking strings, I'd just stick with double quotes here.

While this might be (I'm not 100% sure with that 😁 ) technically correct

This is just a style issue; you can trust Pkl to produce the right thing here.

[StefMa]

Yay, this works 🎉
Thank you @bioball 👏