What is the jsonnet syntax for nested arrays?

Question

I cannot find the way to declare an array in an array with jsonnet. Here is the syntax I would like to render:

git/push/myrules:
  rules:
      - changes:
        - package.json
        - yarn.lock

I do succeed to setup changes as the first element of rules array

local git_push_instance() =
  {
    ['rules']: [
        'changes'
    ]
  };

{
  ['git/push/myrules']: git_push_instance()
}

Here is the output of command line jsonnet rules.jsonnet

{
   "git/push/myrules": {
      "rules": [
         "changes"
      ]
   }
}

But how to setup changes as an array with 2 entries : package.json and yarn.lock ?

I try this but got an error:

local git_push_instance() =
  {
    ['rules']: [
        changes: ['package.json', 'yarn.lock']
    ]
  };

{
  ['git/push/myrules']: git_push_instance()
}

STATIC ERROR: rules.jsonnet:4:16: expected a comma before next array element.

Answer 1

The issue is that below construct has a key (changes:) while supposedly being an array entry:

    ['rules']: [
        changes: ['package.json', 'yarn.lock'] // incorrect
    ]

You need to change the above to emit an array of (mini)objects instead:

    ['rules']: [
        { changes: ['package.json', 'yarn.lock'] },
    ]

Just for completeness, pasting below the src and its output:

rules.jsonnet

local git_push_instance() =
  {
    rules: [
      { changes: ['package.json', 'yarn.lock'] },
    ],
  };

{
  'git/push/myrules': git_push_instance(),
}

output

NB: piping it thru yq -PI2 for a cleaner YAML output:

$ jsonnet rules.jsonnet | yq -PI2
git/push/myrules:
  rules:
    - changes:
        - package.json
        - yarn.lock