The new KiCad file formats are all S-expression based[0], except for the project files which are JSON IIRC. I think it works pretty well for representing a tree

The new KiCad file formats are all S-expression based[0], except for the project files which are JSON IIRC. I think it works pretty well for representing a tree of typed objects textually. They don't even have any LISP connections. Haven't seen S-expressions used anywhere else, though. [0]: https://dev-docs.kicad.org/en/file-formats/sexpr-intro/ https://dev-docs.kicad.org/en/file-formats/sexpr-intro/