[vorg]

> "the only reason you would now use yacc is parsing speed"

Wikipedia says another advantage of LR parsing over LL is the error messages are more localized, and therefore relevant. I wonder whether derivatives in an LL parser (e.g. combinators) would help with that disadvantage?

If not, and because derivatives run quickly in practice for correct grammars, but approach theoretical exponential speed for random inputs, perhaps the best use for derivative grammars is giving realtime feedback when typing code into an IDE which enforces correct input and editing (e.g. always producing a corresponding correctly-placed close bracket in the code somewhere when the programmer types in the open bracket), and only allows previously entered source code to be edited within the IDE. Such a use would give decent parsing speed and no need for error messages, the very function parsing derivatives are good at (assuming this research is correct).