@equivalent Sorry for the late response but we can set the ruby19_syntax: true option but this only works for symbols right now.

I think we definitely could add something like a json_hashes option for this use case.

Or maybe we move has formatting to a new hash_format option with three possibilities like rocket, symbol, and json

I like the idea of hash_format:

:rocket would work for all keys.

:symbol would only affect Symbol keys, while any other keys would be printed in rocket format. Ruby actually allows mixing of Hash literals: {a: 5, :b => 6, 'c' => 4, 2 => 1 }

And :json would convert every key into a String (#to_s) first and then print in JSON format. Should we care about possible duplicate keys? E.g. "a" and :a or "1" and 1 would turn into the same String keys.

It looks like the built in JSON library returns those as duplicate string keys (at least on Ruby 3.0) and converts numbers to strings.

require 'json'
{ a: 'cheese', 'a' => 'burger', 1 => 'fries',  1.0 => 'version' }.to_json
# => "{\"a\":\"cheese\",\"a\":\"burger\",\"1\":\"fries\",\"1.0\":\"version\"}"

I just realized it will only matter when you’re trying to copy paste it into a script or console. And then it’s probably just the last duplicate that wins (if not a syntax error).

What I mean: You’ll still see all the keys if it’s simply used for (debug) logging.

I started working on this a bit and realized we'll want Array to also use JSON format. I'm not sure if hash_format is the best approach for this in that case.

What about output_syntax? Could be default, ruby (no array indexes to make it copy-pastable), json, ...

The main problem here would be nested objects that can't be easily converted to JSON friendly literals. This reminds me of the strict args Sidekiq introduced with Sidekiq 6 and now requires with version 7.