错误 "for/list: missing body expression after sequence binding..." 的原因是什么？

Question

尝试此代码时出现错误：

(define odc (odbc-connect #:dsn DSNNAME #:user USER #:password PASSWORD)); 
(define-struct attendance-event (date flag)#:transparent)

(define-struct list-attendance-events (v)
    #:methods gen:stream
    [(define (stream-empty? stream)
       (empty? (list-attendance-events-v stream)))
     (define (stream-first stream)
       (first (list-attendance-events-v stream)))
     (define (stream-rest stream)
       (rest (list-attendance-events-v stream)))])

(define list-of-events (
(for/list ([(date code)
            (in-query odc "select date, code from attendance
where student_id = ? and term_code = ?
"12345" "654321")]))
(make-attendance-event date code)

我有 for/list 工作，但我改变了一些东西并破坏了它。我可以获得 'first' 元素并且我假设 'last'，以及检查是否为空？

发生了什么事？

Answer 1

也许是这个？

(define list-of-events 
  (for/list ([(date code)
              (in-query odc "select date, code from attendance
                             where student_id = ? and term_code = ?"
                        "12345" "654321")])
    (make-attendance-event date code)))

错误 "for/list: missing body expression after sequence binding..." 的原因是什么？

What is the cause of the error "for/list: missing body expression after sequence binding..."?

racket