Land of Lisp

What You've Learned

In this chapter, we discussed how conditions work in Lisp. Along the way, you learned the following:

• The values nil, 'nil, (), and '() are all basically the same thing in Common Lisp.

• Lisp makes it easy to check for empty lists. This makes it simple to write list-eaters.

• Lisp conditionals, such as the if command, cause Lisp code to be evaluated only under the right conditions.

• If you need a conditional command that does everything, then you want to use cond.

• Comparing stuff in Lisp is complicated, but you can get by if you just use eq for comparing symbols and equal for comparing everything else.