module Pure_map : sig
  type 'a t

  val empty : 'a t
  val add : int -> 'a -> 'a t -> 'a t
  val remove : int -> 'a t -> 'a t
  val find : int -> 'a t -> 'a
  val find_opt : int -> 'a t -> 'a option
  val mem : int -> 'a t -> bool
  val cardinal : 'a t -> int
  val is_empty : 'a t -> bool
  val bindings : 'a t -> (int * 'a) list
  val fold : (int -> 'a -> 'b -> 'b) -> 'a t -> 'b -> 'b
  val iter : (int -> 'a -> unit) -> 'a t -> unit
  val map : ('a -> 'b) -> 'a t -> 'b t
  val keys : 'a t -> int list
  val equal : ('a -> 'a -> bool) -> 'a t -> 'a t -> bool
end

type counters = {
  mutable predicate_evaluations : int;
  mutable mapping_evaluations : int;
  mutable changed_key_visits : int;
  mutable full_traversals : int;
  mutable scalar_deltas : int;
}

val new_counters : unit -> counters
val copy_counters : counters -> counters
val reset_counters : counters -> unit
val count_predicate : counters -> unit
val count_mapping : counters -> unit
val count_changed_key : counters -> unit
val count_full_traversal : counters -> unit
val count_scalar_delta : counters -> unit
val counters_to_string : counters -> string

type 'a outcome = Success of 'a | Failure of string