As verbs the difference between cons and lack
is that
cons is (computing) to obtain a list from a cons or a nesting of conses; to prepend an element to a list by forming a cons of that element and the list; to obtain a list from a smaller one by repeated application of such kind of prepending or
cons can be (
con) while
lack is .
As a noun cons
is or
cons can be (computing) a data structure in lisp that is a pair of pointers, car and cdr, used mainly for lists.