[giaour]

Those are simple expressions (no multiline blocks, no named symbols, no expressions that call other expressions), and you're still forced to treat them as opaque strings when you use a serialization language for configuration.

That may be the best approach for a given project! But if you're using configuration to define an API contract, cloud infrastructure, or a query, you might be better off using a purpose-built DSL like protocol buffers, HCL, or SQL, respectively. That approach can let you define a greater level of expressivity than is allowed in a serialization language like JSON or XML without letting config authors write scripts of arbitrary computational complexity (like they would be able to with config in a scripting language).