Fast list membership using make-lookup-alist.
(fast-memberp a x alist) → *
In the logic, (fast-memberp a x alist) is just a list membership check;
However, our guard requires that
(defun fast-memberp$inline (a x alist) (declare (xargs :guard (set-equiv (alist-keys alist) (list-fix x)))) (let ((__function__ 'fast-memberp)) (declare (ignorable __function__)) (mbe :logic (if (member-equal a x) t nil) :exec (if (hons-get a alist) t nil))))