(defun sum (x) (reduce ‘+ y)
)

You might not have noticed the other parenthesis below. Running this through the REPL in Common Lisp reveals that the function does precisely what was intended,

And yes, haha defunc is certainly wrong, haha I actually write a lot of ACL2S, which is a Lisp derivative. Rather than using defun, they use defunc. Haha so in that regard, certainly mis-typed.

With a removal of the c in defunc, all of the Lisp is valid and executable. Thanks for the catch!