> On 23 Oct 2025, at 01:23, Miek Gieben <[email protected]> wrote: > > [ Quoting <[email protected]> in "[DNSOP] Re: subtyping for fun and > p..." ] >>> Does the language you use have a sum type that has a hard time expressing >>> unknown data? >> >> The Haskell type system is notieably richer than that of Rust, the main >> area where Rust is ahead is "linear" types, which in Haskell are new, >> still evolving, and mostly marginal at present. >> >> "Sum" types are not a good model for types that are extensible, because >> the intoduction of new constructors is an API change: previosly >> "complete" matches, become incomplete when a new variant is added. > > For RRs we fixed this by allowing unknown RRs, which have a presentation > format and a > wireformat, so all is good. But we never did that for unknown rdata fields.
Actually we have. UNKNOWN format handles records where the presentation format is subtype dependent and you don’t know what that format is. If you can’t display the record with a subtype specific format you just display it in UNKNOWN format. BIND has been doing this since UNKNOWN format was proposed. ATMA, APL, ATMRELAY, IPSECKEY, and LOC all fallback to UNKNOWN format for unknown subtypes. > Think this could work for AMTRELAY, I think... for SVCB it might be harder > still because of > the key=value presentation format. > > Kind regards, > Miek > > _______________________________________________ > DNSOP mailing list -- [email protected] > To unsubscribe send an email to [email protected] -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: [email protected] _______________________________________________ DNSOP mailing list -- [email protected] To unsubscribe send an email to [email protected]
