adam@5: (** A record membership predicate *)
adam@5: 
adam@5: con mem :: K --> Name -> K -> {K} -> Type
adam@5: 
adam@5: val mem : K --> nm :: Name -> t :: K -> r :: {K} -> [[nm] ~ r] => mem nm t ([nm = t] ++ r)
adam@5: val mp : K --> K2 --> f :: (K -> K2) -> nm ::: Name -> t ::: K -> r ::: {K} -> mem nm t r -> mem nm (f t) (map f r)
adam@5: 
adam@5: val proj : nm ::: Name -> t ::: Type -> r ::: {Type} -> mem nm t r -> $r -> t
adam@5: val replace : nm ::: Name -> t ::: Type -> r ::: {Type} -> mem nm t r -> $r -> t -> $r
adam@5: 
adam@5: val fold : K --> tf :: ({K} -> Type) -> r ::: {K}
adam@5:            -> (nm :: Name -> v :: K -> r' :: {K} -> [[nm] ~ r']
adam@5:                => mem nm v r -> tf r' -> tf ([nm = v] ++ r'))
adam@5:            -> tf []
adam@5:            -> folder r -> tf r