I have this function that gets 2 parameters - one of them is optional. It does this:
if x is an empty list or not a list return the optional parameter.
else - return a list that contains length(x) and list of last value of x and the optional parameter.
This is the function:
- Code: Select all
(defun lastplus (x &optional (n 0)) ; n is optional parameter with default value of 0
( if (or (not (listp x)) (null x))
(list (length x) (list (nth (- (length x) 1 ) x ) n ) )
I loaded the function to the Listener, but it gives me this error:
CL-USER 2 : 1 > (lastplus 2)
Error: Undefined function N called with arguments ().
I can't understand what am I doing wrong. Could you guys help me?
I am a student at JCT Jerusalem high college of technology.