ambiguity in definitions of purity and side effects

The definitions of purity and side effects are ambiguous. For instance, suppose we have a function that reads, but does modify, state that is reachable from its inputs. Is that a "pure" function? Typically it wouldn't be considered to be pure, but it does not have side effects as-defined, and whether it should be considered to return a value that only depends on its inputs is unclear (since the definition doesn't say that the inputs must be stateless values).

No file, test, or entry point is identified in the issue. Review the existing definitions of purity and side effects and the comment discussion; done means the ambiguity about reading or modifying state reachable from inputs is resolved in the glossary text.