(define eval-and-exp
  (lambda (exp-list env)
    (if (null? exp-list) 
	1
	(let ((val (eval-expression (car exp-list) env)))
	  (if (true-value? val)
	      (eval-and-exp (cdr exp-list) env)
	      0)))))

(define eval-or-exp
  (lambda (exp-list env)
    (if (null? exp-list) 
	0
	(let ((val (eval-expression (car exp-list) env)))
	  (if (true-value? val)
	      1
	      (eval-and-exp (cdr exp-list) env))))))


    (expression ("eval" "(" expression ")") eval-exp)



	   (eval-exp (exp) (eval-program 
			    (scan&parse (eval-expression exp env))))


define swap = fn(a, b) [let (tmp = ^a) in {set a = ^b; set b = tmp;}]