I do this using a mapcar..

`(cond
  ,@(mapcar #'(lambda (event)
            (cond
               ...))
            list-of-events))

..passing it a list-of-events and having it generate the corresponding
clause..

`((eql

..based on a (COND). My problem is that the lambda will return NIL
when no clause is generated, obviously. mapcar then cons this result
onto the result list. This tends to mess up my COND, interspersing the
tests with NIL.

 (defun mapclan (function list &rest lists)
   (loop for args in (zip (cons list lists))
         when (apply function args) collect it))