(* buffer.sig *)

(* CML buffers of length at most one *)

signature BUFFER =
sig

(* a buffer whose elements have type 'a *)

type 'a buffer

(* create a buffer *)

val make : unit -> 'a buffer

(* add(buf, x) adds x to buf, and then returns (); it blocks until the
   addition is possible *)

val add : 'a buffer * 'a -> unit

(* del buf deletes the element of buf, and returns the deleted
   element; it blocks until the deletion is possible *)

val del : 'a buffer -> 'a

end;