type 'a t
type 'a ivar

val return : 'a -> 'a t
val ( >>= ) : 'a t -> ('a -> 'b t) -> 'b t
val ( >>| ) : 'a t -> ('a -> 'b) -> 'b t
val ( >>> ) : unit t -> unit t -> unit t
val both : 'a t -> 'b t -> ('a * 'b) t
val fork : (unit -> 'a t) -> 'a ivar t
val fork_and_join : (unit -> 'a t) -> (unit -> 'b t) -> ('a * 'b) t
val fork_and_join_unit : (unit -> unit t) -> (unit -> unit t) -> unit t
val parallel_map : 'a list -> f:('a -> 'b t) -> 'b list t
val parallel_iter : 'a list -> f:('a -> unit t) -> unit t
val run_process : (unit -> 'a) -> ('a, int) result t
val run : 'a t -> 'a
val set_concurrency : int -> unit
val get_concurrency : unit -> int