Priorities

A typical layered grammar treats highly recursive language constructs with sophisticated priorities by explicitly encoding them in a long streak of nonterminals. A cleaner way would have been to merge all definitions into one nonterminal (or a few conceptually grouped ones) and to define priorities between them.

Reference

Mats Stijlaart and Vadim Zaytsev. 2017. Towards a taxonomy of grammar smells. In Proceedings of the 10th ACM SIGPLAN International Conference on Software Language Engineering (SLE 2017). ACM, New York, NY, USA, 43-54.