DEFINITION MODULE StdIO;
(* Generic character input/output over the default channels, with a
   stack of pushable procedures (gm2-compatible). *)

TYPE
  ProcWrite = PROCEDURE (CHAR);
  ProcRead  = PROCEDURE (VAR CHAR);

PROCEDURE Read (VAR ch : CHAR);
PROCEDURE Write (ch : CHAR);

PROCEDURE PushOutput (p : ProcWrite);
PROCEDURE PopOutput;
PROCEDURE GetCurrentOutput () : ProcWrite;

PROCEDURE PushInput (p : ProcRead);
PROCEDURE PopInput;
PROCEDURE GetCurrentInput () : ProcRead;

END StdIO.