[mcv]

Isn't that a problem with most of these config languages, though? XML is the only one where I think this might be possible.

[wongarsu]

Allowing you to define types is quite uncommon, but many config languages allow more types than JSON (so more than boolean, number, string, list, dict). Date datatypes are a big one and are provided by about every second JSON variant, in addition to TOML, ION and others.