(case (length (cdr form))
(1 `(unary- ,(cadr form)))
(t (reduce (lambda (x y) `(- ,x ,y)) (cdr form)))))
+ ((and or)
+ (reduce (lambda (x y) `(,(car form) ,x ,y)) (cdr form)))
((progn comma)
(reduce (lambda (x y) `(comma ,x ,y)) (cdr form) :from-end t))
(t form))