Help in writing infix macro in CL.

["S. Sridhar" <sridhar%tekecs%tektronix.csnet@CSNET-RELAY.ARPA>]

Is there a way to do the following using the reader macro functions
of CLtL ?

 I want to have a reader macro that translates
 (a + b) to (+ a b). How can I remember the lisp object that was read
 before the macro character #\+.
 
I would appreciate some pointers.


-sridhar