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Char+position

Char+position-p

Recognizer for char+position structures.

Signature
(char+position-p x) → *

Definitions and Theorems

Function: char+position-p

(defun char+position-p (x)
  (declare (xargs :guard t))
  (let ((__function__ 'char+position-p))
    (declare (ignorable __function__))
    (and (mbe :logic (and (alistp x)
                          (equal (strip-cars x) '(char position)))
              :exec (fty::alist-with-carsp x '(char position)))
         (b* ((char (cdr (std::da-nth 0 x)))
              (position (cdr (std::da-nth 1 x))))
           (and (natp char)
                (positionp position))))))

Theorem: consp-when-char+position-p

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