''Сonstraint'' versions of the arithmetic operations

The celsius-fahrenheit-converter procedure is cumbersome when compared with a more expression-oriented style of definition, such as

(define (celsius-fahrenheit-converter x)
  (c+ (c* (c/ (cv 9) (cv 5))
          x)
      (cv 32)))

(define C (make-connector))

(define F (celsius-fahrenheit-converter C))

Here c+ , c* , etc. are the ''constraint'' versions of the arithmetic operations. For example, c+ takes two connectors as arguments and returns a connector that is related to these by an adder constraint:

(define (c+ x y)
  (let ((z (make-connector)))
    (adder x y z)
    z))

Define analogous procedures c- , c* , c/ , and cv (constant value) that enable us to define compound constraints as in the converter example above.

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