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Chase-position

Chase-position-p

Recognizer for chase-position structures.

Signature
(chase-position-p x) → *

Definitions and Theorems

Function: chase-position-p

(defun chase-position-p (x)
 (declare (xargs :guard t))
 (let ((__function__ 'chase-position-p))
   (declare (ignorable __function__))
   (and (mbe :logic (and (alistp x)
                         (equal (strip-cars x)
                                '(path phase rsh mask)))
             :exec (fty::alist-with-carsp x '(path phase rsh mask)))
        (b* ((path (cdr (std::da-nth 0 x)))
             (phase (cdr (std::da-nth 1 x)))
             (rsh (cdr (std::da-nth 2 x)))
             (mask (cdr (std::da-nth 3 x))))
          (and (path-p path)
               (integerp phase)
               (natp rsh)
               (4vmask-p mask))))))

Theorem: consp-when-chase-position-p

(defthm consp-when-chase-position-p
  (implies (chase-position-p x) (consp x))
  :rule-classes :compound-recognizer)