A rule or a query.
t/0 types every field. Three are not obvious:
:namenames the production, but the generated RHS function isrhs_name/1of it instead — a query owns its own name in its module.:bindcomes from the classified LHS, vialhs_bindings/1. So it excludes a negation's variables, and it is the union over a disjunction's branches. A variable only some branches bind is not in every token, so the RHS reads it defensively.:rhsisniluntil the production is escaped. The engine logically inserts and truth-maintains its return value.nilor[]inserts nothing.