Recognizer for feat-endian structures.
(feat-endianp x) → *
Function:
(defun feat-endianp (x) (declare (xargs :guard t)) (let ((__function__ 'feat-endianp)) (declare (ignorable __function__)) (and (consp x) (cond ((or (atom x) (eq (car x) :little)) (and (true-listp (cdr x)) (eql (len (cdr x)) 0) (b* nil t))) (t (and (eq (car x) :big) (and (true-listp (cdr x)) (eql (len (cdr x)) 0)) (b* nil t)))))))
Theorem:
(defthm consp-when-feat-endianp (implies (feat-endianp x) (consp x)) :rule-classes :compound-recognizer)