TOML is more like ini than YAML.

I don't like it because it uses the = symbol which seems imperative rather than declarative. (Same with HCL, it might be a nitpick but these are languages I'm going to be using all the time.)

HOCON is interesting but at first glance it seems it might be too ambiguous for my tastes, because like YAML, because it supports both js-style ("//") and shell-style ("#") comments.

JSON plus comments is beautiful because it adds minimally to an unambiguous language which lends itself to automatic formatting (stringificiation).

I'd argue that = only feels imperative if you're used to imperative languages. Prolog and Haskell, both of which focus on being declarative, also both use the equals sign.

Fair enough. It still seems overkill to me though. A ":" seems much more unassuming than an "=".

Don't forget HJSON if you want a json clone with comments. https://hjson.org/

TOM: Initial release 23 February 2013; 5 years ago

Drupal 8 file format discussion was in 2011, predating it by two years. https://groups.drupal.org/node/159044