(in-package #:safer-lisp)

(define-condition safer-eval-error (safer-lisp-error) ())

(defun %safe-thing (thing)
  (cond
    ((symbolp thing) (%symbol-is-safe-p thing))
    ((listp thing) (every #'%safe-thing thing))
    ;; inline objects are considered safe
    (t t)))

(defun safer-eval (expr)
  "Evaluates expr as if by eval, but only after verifying all symbols in the
expression have been marked as safe."
  (if (%safe-thing expr)
      (eval expr)
      (error 'safer-eval-error
             :format-control "~a not safe!"
             :format-arguments (list expr))))