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Character-kinds

Lcletter-char-p

Recognize lowercase ASCII letters.

Definitions and Theorems

Function: lcletter-char-p

(defun lcletter-char-p (x)
  (declare (xargs :guard t))
  (and (characterp x)
       (b* ((code (char-code x)))
         (and (<= (char-code #\a) code)
              (<= code (char-code #\z))))))

Theorem: booleanp-of-lcletter-char-p

(defthm booleanp-of-lcletter-char-p
  (booleanp (lcletter-char-p x))
  :rule-classes :type-prescription)

Theorem: characterp-when-lcletter-char-p

(defthm characterp-when-lcletter-char-p
  (implies (lcletter-char-p x)
           (characterp x))
  :rule-classes :compound-recognizer)

Subtopics

Lcletter-charlist-p: (lcletter-charlist-p x) recognizes lists where every element satisfies lcletter-char-p.
Lcletter-chars: A character set for lcletter-char-p.