		Search-engine friendly clone of the ACL2 documentation.

Up-alpha-p

Determine if a character is an upper-case letter (A-Z).

Signature
(up-alpha-p x) → bool

ACL2 has a built-in alternative to this function, common-lisp::upper-case-p, which however can also recognize characters that are not standard characters. (Historical note: Before May 2024, the guard for acl2::upper-case-p required standard-char-p yet also converted only standard characters; this provided motivation for the development of up-alpha-p.)

Definitions and Theorems

Function: up-alpha-p$inline

(defun up-alpha-p$inline (x)
  (declare (type character x))
  (let ((acl2::__function__ 'up-alpha-p))
    (declare (ignorable acl2::__function__))
    (b* (((the (unsigned-byte 8) code)
          (char-code x)))
      (and (<= (big-a) code)
           (<= code (big-z))))))

Theorem: chareqv-implies-equal-up-alpha-p-1

(defthm chareqv-implies-equal-up-alpha-p-1
  (implies (chareqv x x-equiv)
           (equal (up-alpha-p x)
                  (up-alpha-p x-equiv)))
  :rule-classes (:congruence))

Theorem: upper-case-p-is-up-alpha-p

(defthm upper-case-p-is-up-alpha-p
  (implies (standard-char-p x)
           (equal (common-lisp::upper-case-p x)
                  (up-alpha-p (double-rewrite x)))))