adam@11: val numFields : r ::: {Type} -> folder r -> $r -> int
adam@11: 
adam@10: val mem : a ::: Type -> ns ::: {Unit} -> eq a -> folder ns -> a -> $(mapU a ns) -> bool
adam@10: (* Is a value found in a record? *)
adam@12: 
adam@12: val equal : ts ::: {Type} -> $(map eq ts) -> folder ts -> $ts -> $ts -> bool
adam@12: (* Are two records equal? *)