Add --dump-format json

[casey]

Closes #989.

To Do

• Document
• Use --format=json instead of --json subcommand
• Mark as --unstable
• Consider using a less weird format for expressions and recipe bodies

[casey]

@dionjwa Have a look at this PR, in particular the tests in tests/json.rs, which show the JSON output.

[casey]

The feature is unstable for now, which means that you have to use the --unstable flag. I did this because I'm a bit unsure of the exact details of the JSON format, and might want to change it based on feedback.

In particular, expressions are serialized in a lispy way which is easy to read, as opposed to the standard rust way. Also, recipes bodies are lists of lists containing either strings, or another list, containing an expression.

so:

foo:
  bar
  {{ baz }}

has:

...
"body":
  [
    // first line, contains recipe text
    ["bar"],
    // second line, contains an interpolation, represented as a list
    // the contents of the interpolation is an expression, in this case `["variable", "baz"]`,
    // which is the same representation of expressions used elsewhere
    [[["variable", "baz"]]],
  ]
...

[casey]

@dionjwa Ping! Let me know if this format is what you were looking for, if you get the chance.

[dionjwa]

Feedback:

Maybe --dump automatically defaults to --dump=json, allowing future formats (unlikely, JSON is too ubiquitous, but?) if/when needed (--dump=yaml or --dump yaml).

As long as the recipe data contains the dependencies, I'm good. The fact that you're actually putting the recipe content there as expressions is just extra awesomeness. I don't need that part right now, but I can easily imagine wanting that in the future since it allows introspection.

Thank you so much!

[casey]

Maybe --dump automatically defaults to --dump=json, allowing future formats (unlikely, JSON is too ubiquitous, but?) if/when needed (--dump=yaml or --dump yaml).

--dump is already used to dump the text contents of a justfile, so making it default to --dump wouldn't be backwards compatible.

As long as the recipe data contains the dependencies, I'm good. The fact that you're actually putting the recipe content there as expressions is just extra awesomeness. I don't need that part right now, but I can easily imagine wanting that in the future since it allows introspection.

Sweet, good to know! What language and library will you use to deserialize the JSON?

Thank you so much!

You bet! This has been a long time coming, so I'm glad to have a user driving it forward.

[casey]

@dionjwa Merged! Let me know how it works for you. Also, if you need me to cut a release so you can experiment with it, let me know.

[dionjwa]

That would be great, but also no rush 👍🏻

[casey]

@dionjwa I released 0.10.4, which includes --dump-format json. Hope it works for you!

[dionjwa]

You're wonderful, thank you! I'll let you know when I finish this crazy esoteric use case I have in mind

[casey]

You bet! Looking forward to it :)