Chapter 3, Modularity, Objects, and State
Exercise 3.3
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#lang sicp
(#%require (only racket/base error))
(define (make-account balance secretpwd)
(define (withdraw amount)
(if (>= balance amount)
(begin (set! balance (- balance amount))
balance)
"Insufficient funds"))
(define (deposit amount)
(set! balance (+ balance amount))
balance)
(define (dispatch pwd m)
(if (eq? secretpwd pwd)
(cond ((eq? m 'withdraw) withdraw)
((eq? m 'deposit) deposit)
(else (error "Unknown request -- MAKE-ACCOUNT"
m)))
(error "Invalid Password")))
dispatch)