Any indent-based-language examples (smaller/simpler than the massive Python or Haskell ones) in antlr/grammars-v4 or elsewhere?

[metaleap]

Now, there's 300 grammars around just here to "study at length" which is exactly what I want to ruthlessly cut down on, to actually Get Stuff Done For Once. 😁

Does anyone know a language among the many mentioned above (or elsewhere, simple minimal .g4) that is indent+line-based such that indented lines (of whatever tokens) become a block/list of "sub-nodes" of the "parent node" (previous dedented line), recursively? Some config language I guess (might keep it simple without the extra prog-lang complexities). Still context-free, unlike YAML (which understandably is not among the ~300 existing grammars — neither is CoffeeScript, the third indent-based lang I know of).

And ideally without needing custom lexing code hacked together in Java/Python/C#/etc...

I can't believe the most common textual representation humans choose to reflect a simple tree cannot be smoothly expressed in the likes of BNF, eBNF or ANTLR's very similar (and otherwise very cool) dialect after all these decades — I and my search-engine searches must be something?