module Force_once: Force_once
type 'a
t
val create : (unit -> 'a) -> 'a t
create f
creates a new force_onceval force : 'a t -> 'a
force t
runs the thunk if it hadn't already been forced, else it raises an
exception.val ignore : unit -> unit t
ignore ()
= create (fun () -> ())val sexp_of_t : ('a -> Sexplib.Sexp.t) -> 'a t -> Sexplib.Sexp.t