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? *)
ezyang@28: 
ezyang@28: (* Analogous to applicative ap e.g. <*>, of type [f (a -> b) -> f a -> f b] *)
ezyang@28: val ap : K --> tf1 :: (K -> Type) -> tf2 :: (K -> Type)
ezyang@28:          -> r ::: {K} -> folder r
ezyang@28:          -> $(map (fn t => tf1 t -> tf2 t) r)
ezyang@28:          -> $(map tf1 r)
ezyang@28:          -> $(map tf2 r)