On Tue, Sep 7, 2010 at 11:15 PM, Daniel Weinreb <dlw@itasoftware.com> wrote:
  

What happens if you do

(defun foo (x)
  (plus x 3))
    

Since (constantp 'x) yields nil, the compiler macro will bail out.

 I
suppose a smarter version could perform some optimizations when only
one of the arguments is constant.

On a related note, I just came across this SBCL effort
<https://bugs.launchpad.net/sbcl/+bug/632368> which has the potential
to make compiler macros significantly more powerful by handing forms
over only after they've been through the compiler's inlining and
constant propagation phases!