;;;; A++ Interpreter Test - Bank Account
;
;;;;

(define make-account 
  (lambda(balance)
    (define get-balance
      (lambda()
        balance))

    (define deposit 
      (lambda(amount)
        (define balance (add balance amount))
        balance))

    (define withdraw 
      (lambda(amount)
        (if (gep balance amount)
             ((lambda()
                (define balance (sub balance amount))
                balance))
             false)))

    (define print-account
      (lambda()
        (ndisp! balance)))

    (define self 
      (lambda(msg)
        (if (equal msg 'get-balance) 
             get-balance
             (if (equal msg 'deposit) 
                  deposit
                  (if (equal msg 'withdraw) 
                       withdraw
                       (if (equal msg 'print) 
                            print-account
                            false)))))) 

    self))

(define konto
  (lambda()
    (define k1 (make-account ten))
    (define k2 (make-account five))
    
    ((k1 'print))
    ((k1 'deposit) ten)
    ((k1 'print))
    ((k1 'withdraw) four)   
    ((k1 'print))   

    ((k2 'print))   
    ((k2 'deposit) nine)   
    ((k2 'print))   
    ((k2 'withdraw) seven) 
    ((k2 'print))
   )) 

(konto)