26 lines
612 B
Scheme
26 lines
612 B
Scheme
(define (make-account balance)
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(define (withdraw amount)
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(if (>= balance amount)
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(begin (set! balance (- balance amount))
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balance)
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"Insufficient funds"))
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(define (deposit amount)
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(set! balance (+ balance amount))
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balance)
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(define (dispatch m)
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(cond ((eq? m 'withdraw) withdraw)
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((eq? m 'deposit) deposit)
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(else (error "Unknown request -- MAKE-ACCOUNT"
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m))))
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dispatch)
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(define acc (make-account 100))
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((acc 'withdraw) 50)
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50
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((acc 'withdraw) 60)
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"Insufficient funds"
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((acc 'deposit) 40)
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90
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((acc 'withdraw) 60)
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30
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