Uncluster

Nonterminals that refer to one another, should be located close to one another. The longer the distance between the use of a nonterminal from its definition, the more the reader of the grammar will have to switch context. A lot of scrolling always means there is something smelly about how the gram- mar is set up. Moving the production rules that cause the scrolling closer to each other to form a cluster, will result in an easier grammar with more coherent structure.

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.