David Roundy
I'd benefit from just a list of problems that the record proposals want to solve.
1. The field namespace issue. 2. Multi-constructor getters, ideally as a function. 3. "Safe" getters for multi-constructor data types. 4. Getters for multiple data types with a common field. 5. Setters as functions. 6. Anonymous records. 7. Unordered records.
Personally, I would quite like to have "first-class labels". By this I mean the ability to pass record labels as arguments, and to return them as results. With this one generalisation, it would be possible to cover most of the wishlist above. A generic getter and setter could be defined simply as polymorphic functions e.g. get :: Label n -> Record (n::a | r) -> a set :: Label n -> a -> Record r -> Record (n::a | r) upd :: Label n -> (a->a) -> Record (n::a | r) -> Record (n::a | r) You could even define your own preferred syntactic sugar for these operations e.g. r . l = get l r .. and the higher-order uses fall out for free map (get foo) listOfRecords There are several proposals incorporating this idea. Oleg Kiselyov and Ralf Lämmel, "Haskell's overlooked object system" http://homepages.cwi.nl/~ralf/OOHaskell/ Daan Leijen, "First-class labels for extensible rows" http://www.cs.uu.nl/~daan/pubs.html Benedict Gaster and Mark Jones, "A Polymorphic Type System for Extensible Records and Variants" http://www.cse.ogi.edu/~mpj/pubs/polyrec.html Regards, Malcolm