adamc@915: con dlist :: Type -> Type
adamc@915: type position
adamc@915: 
adamc@915: val create : t ::: Type -> transaction (dlist t)
adamc@915: val clear : t ::: Type -> dlist t -> transaction unit
adamc@915: val append : t ::: Type -> dlist t -> t -> transaction position
adamc@915: val delete : position -> transaction unit
adamc@915: val elements : t ::: Type -> dlist t -> signal (list t)
adamc@915: 
adamc@915: val render : ctx ::: {Unit} -> [ctx ~ body] => t ::: Type
adamc@915:              -> (t -> position -> xml (ctx ++ body) [] [])
adamc@915:              -> dlist t
adamc@915:              -> xml (ctx ++ body) [] []