Add cl21:require because it is commonly used without cl: prefix.
Add PAPPLY-like reader macro.

 #'(list (1+ _)) => (lambda (param0) (list (1+ param0)))
 #'(list _ (1+ _) _) => (lambda (param0 param1 param2) (list param0 (1+ param1) param2))
 #'(apply #'list _ (1+ _) _...) => (lambda (param0 param1 &rest param2) (apply #'list param0 (1+ param1) param2))
Add flatten.
Delete destructuring-case because it isn't usuful very much.
Allow re-match, re-replace and re-split to take a regular expression as a string, not only a function.