DEFINITION MODULE SysIO;
(* Minimal system I/O, bound to the runtime shim (libc write). *)

PROCEDURE Write(VAR s : ARRAY OF CHAR);
(* Writes the string to standard output (no newline). *)

PROCEDURE WriteLn;
(* Writes a newline to standard output. *)

PROCEDURE WriteInt(n : INTEGER);
(* Writes n in decimal to standard output. *)

PROCEDURE WriteChar(c : CHAR);
(* Writes a single character to standard output. *)

PROCEDURE ReadChar() : CHAR;
(* Reads one character from standard input (0C at end of file). *)

PROCEDURE ReadInt() : INTEGER;
(* Reads a signed decimal integer, skipping leading whitespace. *)

END SysIO.