Almost done with chapter 11 of Build Your Own Lisp and I have finally variables (that are immutable actually) and you can do some funky stuff with them. This is maybe very basic for any lisp but I have never used a lisp.

lzp> def {arglist} {a b x y}
()   
lzp> arglist
{a b x y}
lzp> def arglist 1 2 3 4
()   
lzp> list a b x y
{1 2 3 4}