(* buffer.sig *)

(* CML buffers with adjustable maximum lengths *)

signature BUFFER =
sig

(* a buffer whose elmements come from type 'a *)

type 'a buffer

exception Size

(* create a buffer with a given maximum length; raises Size if
   the length is not positive *)

val make : int -> 'a buffer

(* addEvt buf x returns an event that, when synchronized with, will
   cause x to be added to the end of buf, and will yield () *)

val addEvt : 'a buffer -> 'a -> unit CML.event

(* delEvt buf returns an event that, when synchronized with, with
   remove the first element from buf, and will yield this element *)

val delEvt : 'a buffer -> 'a CML.event

(* lenEvt buf returns an event that, when synchronized with, will
   yield the current length of buf *)

val lenEvt : 'a buffer -> int CML.event

(* newMaxLenEvt buf n returns an event, that when synchronized with,
   will attempt to set the maximum length of buf to n

   this attempt will succeed, resulting in the value true,
   if the current length of buf is no more than n

   this attempt will fail, resulting in the value false,
   if the current length of buf is strictly greater than n *)

val newMaxLenEvt : 'a buffer -> int -> bool CML.event

end;