-- Code of Figure 9.8, page 376 from
-- Kenneth C. Louden, Programming Languages
-- Principles and Practice 2nd Edition
-- Copyright (C) Brooks-Cole/ITP, 2003
-- With improvements described on page 377

package ComplexNumbers is

type Complex is private;

function "+"(x,y: in Complex) return Complex;
-- add the following functions later
--function "-"(x,y: in Complex) return Complex;
--function "*"(x,y: in Complex) return Complex;
--function "/"(x,y: in Complex) return Complex;
--function "-"(z: in Complex) return Complex;
function makeComplex (x,y: in Float) return Complex;
function realPart (z: in Complex) return Float;
function imaginaryPart (z: in Complex) return Float;

private
   type ComplexRecord;
   -- incomplete type defined in package body 
   type Complex is access ComplexRecord;
   -- a pointer type
end ComplexNumbers;