eopl 2.12

exercise-2.12.rkt

(define (empty-stack)
  (lambda (action)
    (cond ((eq? action 'top)
            (repo-empty-stack-err))
          ((eq? action  'empty)
            #t)
          ((eq? action 'pop)
            (repo-empty-stack-err))
          (else (repo-no-support-err)))))
          
(define (push stack var)
  (lambda (action)
    (cond ((eq? action  'top) var)
          ((eq? action  'empty) #f)
          ((eq? action  'pop) stack)
          (else (repo-no-support-op)))))

(define (top  stack)
  (stack 'top))
(define (empty-stack? stack)
  (stack  'empty?))
(define (pop  stack)
  (stack  'pop))