Grammy Award for Best Male Pop Vocal Performance

To implement that function, you can dip into the bag of advanced Lisp tricks and pull out the mighty and powerful LOOP macro. (defun make-comparisons-list (fields) (loop while fields collecting (make-comparison-expr (pop fields) (pop fields)))) A full discussion of LOOP will have to wait until Chapter 22; for now just note that this LOOP expression does exactly what you need: it loops while there are elements left in the fields list, popping off two at a time, passing them to make-comparison-expr, and collecting the results to be returned at the end of the loop. The POP macro performs the inverse operation of the PUSH macro you used to add records to *db*. Now you just need to wrap up the list returned by make-comparison-list in an AND and an anonymous function, which you can do in the where macro itself. Using a back quote to make a template that you fill in by interpolating the value of make-comparisons-list, it's trivial. (defmacro where (&rest clauses) `#'(lambda (cd) (and ,@(make-comparisons-list clauses)))) This macro uses a variant of , (namely, the ,@) before the call to make-comparisons-list ...»