Others have explained why the Chomsky Hierarchy isn't particularly useful to people working on designing or implementing languages. What IS useful and which dev

Others have explained why the Chomsky Hierarchy isn't particularly useful to people working on designing or implementing languages. What IS useful and which developed around the same time as Chomsky's theories is BNF notation: https://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form https://en.wikipedia.org/wiki/Backus%E2%80%93Naur_Form