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Eprefix

Eprefixp

Recognizer for eprefix structures.

Signature
(eprefixp x) → *

Definitions and Theorems

Function: eprefixp

(defun eprefixp (x)
  (declare (xargs :guard t))
  (and (consp x)
       (cond ((or (atom x) (eq (car x) :locase-u8))
              (and (eq (cdr x) nil) (b* nil t)))
             ((eq (car x) :locase-u)
              (and (eq (cdr x) nil) (b* nil t)))
             ((eq (car x) :upcase-u)
              (and (eq (cdr x) nil) (b* nil t)))
             (t (and (eq (car x) :upcase-l)
                     (and (eq (cdr x) nil))
                     (b* nil t))))))

Theorem: consp-when-eprefixp

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