Major Section: ACL2-BUILT-INS
(Alpha-char-p x) is true if and only if x is a alphabetic character,
i.e., one of the characters #\a, #\b, ..., #\z, #\A,
#\B, ..., #\Z.
The guard for alpha-char-p requires its argument to be a character.
Alpha-char-p is a Common Lisp function. See any Common Lisp
documentation for more information.
To see the ACL2 definition of this function, see pf.