Alpha-char-p
Recognizer for alphabetic characters
(Alpha-char-p x) is true for a character x if and only if
x is alphabetic, i.e., one of the characters #\a, #\b,
..., #\z, #\A, #\B, ..., #\Z.
The guard for alpha-char-p states that its argument is a
character.
Alpha-char-p is a Common Lisp function. See any Common Lisp
documentation for more information. Note that the value returned may depend
on the host Lisp; see soundness, specifically Example 1 in the Section,
“Examples of divergence among Lisp implementations”.
Function: alpha-char-p
(defun alpha-char-p (x)
(declare (xargs :guard (characterp x)))
(cond ((standard-char-p x)
(and (member x
'(#\a #\b #\c
#\d #\e #\f #\g #\h #\i #\j #\k #\l #\m
#\n #\o #\p #\q #\r #\s #\t #\u #\v #\w
#\x #\y #\z #\A #\B #\C #\D #\E #\F #\G
#\H #\I #\J #\K #\L #\M #\N #\O #\P #\Q
#\R #\S #\T #\U #\V #\W #\X #\Y #\Z))
t))
(t (alpha-char-p-non-standard x))))
