This is a command-line RPN calculator program implemented in Common Lisp.

luc's biggest advantage is the use of Common Lisp's native number types,
e.g. bignums. Type "69 fac" to see what I mean.

Type "help" to get a very short introduction, "functions" to get a list
of the supported functions, and "'fun desc" to get a description of the
function "fun".

Despite its power, I have more or less abandoned luc in favour of
its derivative "lic" that comes with my Lisp interpreter "lingo"
(see https://git.w21.org/lisp/lingo/blob/master/l/lic).