6 Symbols
type
> (symbolp 'apple) t
> (symbolp 'pear) t
> (symbolp 'antigo) t
> (symbolp 't) t
> (symbolp 'nil) t
> (symbolp 5) nil
> (symbolp "I'm a string") nil
> (symbolp (cons 'water (cons 'melon nil))) nil
> (symbolp 'watermelon) t
Warning: t and nil happen to be both symbols and booleans, and nil is a list as well. This means when you’re using symbolp on something that could be a boolean or a list, you might get t even if you didn’t intend for it to be interpreted that way. Be careful when mixing symbols with booleans or lists.
> (symbolp nil) t
> (booleanp nil) t
> (tlp nil) t
> (symbolp t) t
> (booleanp t) t