תכנית לדוגמא

(define checkbook (lambda () 
 
; This check book balancing program was written to illustrate 
; i/o in Scheme. It uses the purely functional part of Scheme. 
 
        ; These definitions are local to checkbook 
        (letrec 
 
            ; These strings are used as prompts 
 
           ((IB "Enter initial balance: ") 
            (AT "Enter transaction (- for withdrawal): ") 
            (FB "Your final balance is: ") 
 
            ; This function displays a prompt then returns 
            ; a value read. 
 
            (prompt-read (lambda (Prompt) 
 
                  (display Prompt) 
                  (read))) 
 
            ; This function recursively computes the new 
            ; balance given an initial balance init and 
            ; a new value t.  Termination occurs when the 
            ; new value is 0. 
 
            (newbal (lambda (Init t) 
                  (if (= t 0) 
                      (list FB Init) 
                      (transaction (+ Init t))))) 
 
            ; This function prompts for and reads the next 
            ; transaction and passes the information to newbal 
 
            (transaction (lambda (Init) 
                      (newbal Init (prompt-read AT))))) 
 
; This is the body of checkbook;  it prompts for the 
; starting balance 
 
  (transaction (prompt-read IB)))))