You can use recursion and template types to type some pretty complex string values now - I've seen cut down parsers for both SQL and TS written just via TS type

You can use recursion and template types to type some pretty complex string values now - I've seen cut down parsers for both SQL and TS written just via TS types which is madness but does show what can be done. Whether the effort is worth it is, however, a totally different question to whether it's possible.