Question

For example, if I had the atom ‘ABCD, is there a way to determine the individual characters that make up the atom?

Answer 1

To get the list of characters in the symbol:

(coerce (string 'ABCD) 'list) ; => (#\A #\B #\C #\D)

You can perform any sort of usual string analysis on a symbol if you first convert it:

(string 'ABCD)                ; => "ABCD"
(char (string 'ABCD) 0)       ; => #\A
(subseq (string 'ABCD) 0 2)   ; => "AB"