Panini's grammar describes Sanskrit syntax and morphology, and it's structured much like a typical parser generator grammar, except written in a heavily abbreviated form of Sanskrit instead of a programming language. In fact it's the first formal grammar in recorded history of any language, and western linguists studying it is arguably is the reason we have the concept of a formal grammar. https://en.wikipedia.org/wiki/A%E1%B9%A3%E1%B9%AD%C4%81dhy%C...