------------------------------------------------------------------------
--								      --
-- NAME:	The Four Seasons				      --
-- AUTHOR:	Antonio Davivli					      --
-- DATE:	1983						      --
--								      --
------------------------------------------------------------------------
						-- C*T Interpreter features
with TEXT_IO; 			-- We will use text_io to printout
use TEXT_IO;			-- our seasons.

procedure FOUR_SEASONS is

   -- Define the SEASONS as an enumeration type.
   type SEASONS is (WINTER, SPRING, SUMMER, FALL);

   -- Create two SEASONS initialized to WINTER.
   THIS_SEASON,NEXT_SEASON : SEASONS:=WINTER;

   -- Define a generic CYCLIC_SUCC that will find the
   -- successor of an enumeration literal (for the
   -- instantiated enumeration type).
   generic					-- generics
     type T is (<>);

   function CYCLIC_SUCC(X:T) return T;

   function CYCLIC_SUCC(X:T) return T is
   begin
     if X=T'LAST then return T'FIRST;	-- Cycle on the boundary condition.
     else return T'SUCC(X);		-- Otherwise take its successor.
     end if;
   end CYCLIC_SUCC;

   -- Instantiate cyclic_succ for seasons so that we
   -- can describe the rotation of the seasons.
   function SEASON_SUCC is new CYCLIC_SUCC(SEASONS);

--	Print out a few examples of season rotation.

begin
   for EXAMPLE in 1 .. 10 loop
     THIS_SEASON:=NEXT_SEASON;
     NEXT_SEASON:=SEASON_SUCC(NEXT_SEASON);
     PUT("The season after ");
     PUT(SEASONS'IMAGE(THIS_SEASON));		-- type attributes
     PUT(" is ");
     PUT_LINE(SEASONS'IMAGE(NEXT_SEASON));
   end loop;
end FOUR_SEASONS;
  
------------------------------------------------------------------------