GraSs: A Taxonomy of Grammar Smells

Organisation
global problems

Navigation
problems with navigating through the grammar

Structure
harmful relationships among grammar components

Convention
violations of visual policies

Notation
metalanguage-related

Parsing
parsing techniques related smells

Duplication
the same fragment is repeated

Underuse
inferior substitutes are used instead of an available feature

Overspec
the same constraint specified through several means

Priorities
not present or circular

Singleton
trivial choice, sequence or conjunction

Combo
double modifier creates an ambiguity

Chant
comments cover up bad code

Deprecated
the use of a feature that is no longer welcome

Exotic
too idiosyncratic notational features decrease portability

Deprecated Edit!

Related smells: Deprecated Statement Usage

Similarly to deprecated statements and methods in programming, grammar notations may have some functionality that is no longer considered viable and proper in the new version. This does not happen all that often, but it may.

The GraSs taxonomy is a joint effort maintained by Dr. Vadim Zaytsev a.k.a. @grammarware. Page last updated in March 2021.