The suffix is just "p" in Common Lisp[1], so I think the "predicate" explanation is more likely to be correct than the visual analogy to the question mark. [1]

The suffix is just "p" in Common Lisp[1], so I think the "predicate" explanation is more likely to be correct than the visual analogy to the question mark. [1] http://www.lispworks.com/documentation/HyperSpec/Body/f_listp.htm http://www.lispworks.com/documentation/HyperSpec/Body/f_list...