(in-package :maxima)

(defvar errset nil)

;;here is the  desired behavior of errset
;;(let ((errset t)) (errset (+ 2 'a))) ;==> signals error
;;(let ((errset nil)) (errset (+ 2 'a))) ;==> nil
;;(let ((errset nil)) (errset (+ 2 3))) ;==> (5)

(defmacro errset (&rest l)
  `(handler-case (list ,(car l))
    (error (e) (when errset (error e)))))

;;a generic one if you have no error handling 
;;at all, that caught no errors but at least
;;returned a list in the normal case would be 
;; (defmacro errset (&rest l) `(list ,(car l)))