Representation of rectangles on a plane

Implement a representation for rectangles in a plane. (Hint: You may want to make use of exercise 2.2 ). In terms of your constructors and selectors, create procedures that compute the perimeter and the area of a given rectangle. Now implement a different representation for rectangles. Can you design your system with suitable abstraction barriers, so that the same perimeter and area procedures will work using either representation?

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