- The CASE function
- The MAP function
- Backticks

I also didn’t know about the STRING-DOWNCASE function, but that one’s easy to understand: it just converts a string to lower-case.

Perhaps I’ll explore these suggestions further in my next post.

I think I might do things a little differently. It’s really handy to treat strings as vectors of characters (which they are) and work on the vectors directly.

Also, using strings like “consonant” or “vowel” will be slower than using a keyword like :consonant or :vowel. Here’s how I might try the same task:

(defun letter-type (char) (case char ((#\a #\e #\i #\o #\u) :vowel) (t :consonant)))

(defun analyze-word (word)
(map ‘list ‘letter-type (string-downcase word))