Char-equal
Character equality without regard to case
For characters x and y, (char-equal x y) is
true if and only if x and y are the same except perhaps for their
case.
The guard on char-equal states that its arguments are both
characters.
Char-equal 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: char-equal
(defun char-equal (x y)
(declare (xargs :guard (and (characterp x) (characterp y))))
(eql (char-downcase x)
(char-downcase y)))
