error-handling - 方案: Why am I getting this error: assertion-violation: argument of wrong type [car (car #{Unspecific})

Question

我相信我已经在程序中发现它是这个函数，但是在到达find_best_candidates函数的第一行之前似乎失败了:

(define (count-the-score candList voterList)
    (display "Spot 3")
    (cond
        ((null? voterList) 0)
        
        (else
            (cond 
                ((or (= (car candList) 0) (= (car voterList) 0)) (+ 0 (count-the-score (cdr candList)(cdr voterList))))
                ((equal? (car candList) (car voterList)) (+ 1 (count-the-score (cdr candList)(cdr voterList))))
                (else (- (count-the-score (cdr candList) (cdr voterList)) 1))
            )
        )
    )
)

(define (find-max myList)
    (define sortedList 0)
    (display "Spot 4")
    (cond 
        ((null? myList) myList)
        ((null? (cdr myList)) myList)
        
        (else
            (set! sortedList (find-max (cdr myList)))
            
            (cond   
                ((null? sortedList) (cdr myList))
                ((null? (car sortedList)) (car myList))
                ((null? (car myList)) sortedList)
                ((= (car (cdr (car myList))) (car (cdr (car sortedList))))
                 (append sortedList (list (car myList)))
                 )
                 ((> (car (cdr (car myList))) (car (cdr (car sortedList))))
                  (list (car myList))
                )
                
                (else 
                    sortedList
                )
            )
            (display "Spot 5")
        )
    )
)

(define (find_best_candidates Voter Candidates)
    (display "Spot 2")
    (define best 0)
    (define score 0)
    (define voterScore 0)
    (define tempScore 0)
    (define max_till 0) 
    
    (cond 
        ((null? Candidates) '())
        
        (else
            (set! best (find_best_candidates Voter (cdr Candidates)))
            
            (set! score (count-the-score Voter (cdr (car Candidates))))
            
            (set! voterScore (list (car (car Candidates)) score))
            
            (set! tempScore (append best (list voterScore)))
            
            (set! max_till (find-max best))
            
        )
    )
    (display "Spot 6")
)


(define (fetch-names myList)
    (display "Spot 7")
    (define prev_ans 0)
    (define ll 0)
        (cond 
            ((null? (cdr myList)) (list(car (car myList))))
            
            (else 
                
                (set! prev_ans (fetch-names (cdr) myList))
                
                (set! ll (append (list (car (car myList))) prev_ans))
                ll
            )   
        )
        (display "Spot 8")
        
)


;Main function;
(define (best_candidates Voter Candidates)
    (display "Spot 1")
    (fetch-names (find_best_candidates Voter Candidates))
    (display "Spot END")
)

导入的数据如下:

(define (test1)
(best_candidates 
    '(           0   0   0   1   1   1  -1  -1  -1   1)
    '((Adams     1   1   1   1   1   1   1   1   1   1)
      (Grant    -1  -1  -1  -1  -1  -1  -1  -1  -1  -1)
      (Polk      1  -1   1  -1   1  -1   1  -1   1  -1)
      (Jackson   1   0   1   0   1   0   1   0   1   0)
      (Taft      0  -1   0  -1   0  -1   0  -1   0  -1)
      (Ford      1   1   1   1   0   0   0   0   0   0)
      (Madison   0   0   0   1  -1   0   0  -1   1   1)))
)
; should return (adams ford madison)

我最终收到的错误是:

assertion-violation: argument of wrong type [car]
                     (car #{Unspecific})

Answer 1

找到了我的问题。在fetch-names函数中，我有(set! prev_ans (fetch-names (cdr) myList))，应将其写为(set! prev_ans (fetch-names (cdr myList)))。我放错了括号。