Recognize strings of the form
(vls-datestr-p x) → *
Function:
(defun vls-datestr-p (x) (declare (xargs :guard (stringp x))) (let ((__function__ 'vls-datestr-p)) (declare (ignorable __function__)) (and (<= 10 (length x)) (str::dec-digit-char-p (char x 0)) (str::dec-digit-char-p (char x 1)) (str::dec-digit-char-p (char x 2)) (str::dec-digit-char-p (char x 3)) (eql (char x 4) #\-) (str::dec-digit-char-p (char x 5)) (str::dec-digit-char-p (char x 6)) (eql (char x 7) #\-) (str::dec-digit-char-p (char x 8)) (str::dec-digit-char-p (char x 9)))))