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 andequal
for comparing everything else.
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