type batch = {tuples: Concepts.Tuple.t BatFingerTree.t; exhausted: bool}
type t

class type implementation = object
  method fetch : int -> (batch, Concepts.Condition.condition) result
end

val make : #implementation -> Handle.protocol
val from : Handle.t -> t Handle.interface option
val require : Handle.t -> (t Handle.interface, Concepts.Condition.condition) result
val fetch : t Handle.interface -> int -> (batch, Concepts.Condition.condition) result
val next : t Handle.interface -> (Concepts.Tuple.t option, Concepts.Condition.condition) result

val exists :
  t Handle.interface -> (Concepts.Tuple.t -> bool) -> (bool, Concepts.Condition.condition) result

val drain :
  t Handle.interface ->
  ?limit:int ->
  unit ->
  (Concepts.Tuple.t BatFingerTree.t, Concepts.Condition.condition) result

(** [f] over [cursor], which is released once [f] returns. *)
val consuming :
  Handle.t ->
  (t Handle.interface -> ('a, Concepts.Condition.condition) result) ->
  ('a, Concepts.Condition.condition) result