Question

I’m just starting off with Lisp and need some help. This is technically homework, but I gave it a try and am getting somewhat what I wanted:

(defun speed (kmp)  
  (cond ((> kmp 100) "Fast")    
        ((< kmp  40) "Slow") 
        (t           "Average")))

However, if I run the program it displays "Average" instead of just Average (without the quotes).

How can I get it to display the string without quotes?

Answer 1

You can also use symbols instead of strings:

(defun speed (kmp)  
  (cond ((> kmp 100) 'fast)    
        ((< kmp  40) 'slow) 
        (t           'average)))

Symbols are uppercased by default, so internally fast is then FAST.

You can write any symbol in any case and with any characters using escaping with vertical bars:

|The speeed is very fast!|

Above is a valid symbol in Common Lisp and is stored internally just as you write it with case preserved.