CODEWITHSUNDEEP
lisp
Ian-Fogelman
Ian-Fogelman

Reputation: 1605

Nil Value From Lisp Function

Why does the following code return a nil value instead of 1?

(defun test (list)
                  (car(list)))

(test '( 1 2 3))

Upvotes: 1

Views: 49

Answers (1)

GDP2
GDP2

Reputation: 2008

It returns nil because you're asking what the car of (list) is, which is a function invocation of the list function. Since you're passing the list function no arguments, it is returning nil since there is no car nor cdr (it's an empty list). The following would produce the desired effect:

(defun test (list)
  (car list))
(test '(1 2 3)) ;; now returns 1

Upvotes: 3

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