		Search-engine friendly clone of the ACL2 documentation.

Isuffix

Isuffixp

Recognizer for isuffix structures.

Signature
(isuffixp x) → *

Definitions and Theorems

Function: isuffixp

(defun isuffixp (x)
  (declare (xargs :guard t))
  (let ((__function__ 'isuffixp))
    (declare (ignorable __function__))
    (and (consp x)
         (cond ((or (atom x) (eq (car x) :u))
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 1)
                     (b* ((unsigned (std::da-nth 0 (cdr x))))
                       (usuffixp unsigned))))
               ((eq (car x) :l)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 1)
                     (b* ((length (std::da-nth 0 (cdr x))))
                       (lsuffixp length))))
               ((eq (car x) :ul)
                (and (true-listp (cdr x))
                     (eql (len (cdr x)) 2)
                     (b* ((unsigned (std::da-nth 0 (cdr x)))
                          (length (std::da-nth 1 (cdr x))))
                       (and (usuffixp unsigned)
                            (lsuffixp length)))))
               (t (and (eq (car x) :lu)
                       (and (true-listp (cdr x))
                            (eql (len (cdr x)) 2))
                       (b* ((length (std::da-nth 0 (cdr x)))
                            (unsigned (std::da-nth 1 (cdr x))))
                         (and (lsuffixp length)
                              (usuffixp unsigned)))))))))

Theorem: consp-when-isuffixp

(defthm consp-when-isuffixp
  (implies (isuffixp x) (consp x))
  :rule-classes :compound-recognizer)