> Using a function to query a fact about a string does not imply that the string should change, ... then there's nothing implementation-quirk about that. Fair

> Using a function to query a fact about a string does not imply that the string should change, ... then there's nothing implementation-quirk about that. Fair enough when considering only the string value. My ill-expressed point was more about JSON as a data exchange format - it may pass through any number of JSON parser/storage implementations, any of which may use an arbitrary order for the keys.