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;; This file contains starter macros and functions for a very
;; simple first order logic implementation


;;; A simple function that returns all the symbols interned in a set
;;; of packages. If no packages are specified then symbols from the
;;; USER package are returned.  For this assignment feel free to call
;;; with no arguments.
(defun get-lisp-symbols (&rest packages)
  (unless packages (setf packages '(user)))
  (let ((ret nil))
    (dolist (package packages ret)
      (do-symbols (sym package)
	(push sym ret)))))

;;; A simple macro that accepts a first order sentence in LISP syntax
;;; and a domain, executing that sentence in that domain.
;;;
;;; In particular, prove executes domain and stores the result in the
;;; global variable *domain* which is accessible by executing the
;;; form: (domain)
(defvar *domain* nil)
(defmacro prove (form domain)
  `(let ((*domain* ,domain))
     ,form))
(defun domain () *domain*)