Question

Well, I am trying to use an element of function list.But i am having problem to use it in my code.

(func (list sum) (list 1 2 3)) i am trying to apply sum element in the list1 to my list2 . sum is described as taking list as argument. I just took one function in list1 for try. However

    (display (car list1)) --> sum
    (display list2)--->(1 2 3)
    (display (list (sum list2)))--->(6)
    (display ((car list1) list2))---> ERROR 

ERROR:function call: expected a function after the open parenthesis, but received ‘sum

I can’t understand why it does give this error. As you see (car list1) refers to sum and list2 refers to (1 2 3) llpist.

Can you tell me if i got anything wrong? Thx.

Answer 1

We need to see the implementation of sum and the exact way you’re creating the lists, I’m guessing that you’re passing the symbol 'sum and not the procedure sum. When I try the following it works without the problem you’re reporting:

; this is guesswork, OP didn't provide enough information
(define sum (lambda (lst) (apply + lst)))
(define list1 (list sum))
(define list2 (list 1 2 3))

(display (car list1))
(display list2)
(display (list (sum list2)))
(display ((car list1) list2)) ; this works for me