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Logical xor: whether one or the other proposition is true (but not both)

x

A proposition

y

Another proposition

(define-syntax
  xor
  (lambda (expression rename compare)
    (match expression
           ((_ x y)
            (let ((%or (rename 'or)) (%and (rename 'and)) (%not (rename 'not)))
              `(,%and (,%or ,x ,y) (,%not (,%and ,x ,y))))))))