If you are using so many local variables that it is becoming a problem, you might need to reorganize. However, I would suggest declaring them all at the beginning and only losing one indentation level.
arc> (with (a 1 b nil) (= b a) b)
1
arc> b
Error: "reference to undefined identifier: _b"
Amen. Try to think more functionally. "On Lisp" is available on-line, see chapter 3. The funny thing is that one can achieve good functional style by making one's code look a certain way.
